Food Adulterants 



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EDWIN A-BRUCE 



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Revised Edition 




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COPYRIGHT DEPOSIT 



Digitized by the Internet Archive 
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Detection of the Common 
Food Adulterants 



BY 

EDWIN M. BRUCE 

PROFESSOR OF CHEMISTRY, HEAD OF DEPARTMENT 
INDIANA STATE NORMAL SCHOOL 



THIRD EDITION 
REVISED AND ENLARGED 




NEW YORK 
D. VAN NOSTRAND COMPANY 

25 Park Place 
1917 



Copyright, 1907, 1917 
By D. Van Nostrand Company 






NOV 30 !S!7 

The Plimpton Press Norwood Mass. U.S.A. 



©CLA479327 

hi 



PREFACE TO THE THIRD EDITION 

It is very gratifying to all who have been engaged in 
the crusade against the adulteration of foods, which was 
so prevalent a few years ago, to mark the great success 
which has been attained. No small part of the success 
has been due to the chemical examination of the foods. 
Health officers, chemistry teachers and pupils, those in 
domestic science and the homes themselves, throughout 
the country are becoming more or less proficient in the 
simple qualitative tests which reveal the true quality of 
the various food products. With this host of inspectors 
it is hoped that the poisoning of foods will be only a 
matter of memory. 

This book has been revised so that it contains the 
latest and best tests for the common food adulterants. 
The author wishes to take this opportunity to express 
his thanks to the various Clubs which have indorsed the 
book, hoping this revised form will still meet their ap- 
proval. 

Terre Haute, Ind. 
Sept. 29, 1917. 



PREFACE TO FIRST EDITION 

Because of the recent agitation of the pure food ques- 
tion throughout the country, health officers, food-inspectors, 
and chemistry teachers and students are constantly called 
upon to test the purity of various foods. And this usually 
involves nothing more than making simple qualitative tests 
for adulterants. In view of the fact that there is now no 
text or manual devoted exclusively to the qualitative exam- 
ination of foods, this little book is offered to those who are 
interested in this work. 

Its aim is to bring together in one small book the best and 
simplest qualitative tests for all the common food adulter- 
ants. It contains a brief statement of the adulterants 
likely to be found and the reason for their use. It is hoped 
that it will be specially valuable to chemistry teachers in 
furnishing excellent supplementary work in qualitative 
analysis. But it is hoped that it will find its greatest use- 
fulness in contributing something toward the great pure 
food reform. 

It is impossible to make due mention of all the sources 
from which these various tests have been collected, but 
where possible, the author's name has been associated with 
the test. 

Terre Haute, Ind. 
March 25, 1907. 



TABLE OF CONTENTS 

CHAPTER I 

Dairy Products i 

Milk — Purity of milk, dirt, hair, etc. — Adultera- 
tions of — Coloring matters — Annatto — Caramel — 
Coal-tar colors — Preservatives — Formaldehyde — 
Boric acid — Salicylic acid — Gelatin — Starch. 

Butter — Adulterations of — Coloring matter — 
Preparation of sample — Annatto — Coal-tar colors 

— Saffron — Turmeric — Marigold — Process or reno- 
vated butter — Oleomargarine — Cottonseed oil. 

CHAPTER II 
Meat and Eggs 10 

Adulterations of — Fresh and smoked — Preserva- 
tives — Potassium nitrate — Boric acid — Sulfurous 
acid — Salicylic acid — Benzoic acid — Canned — 
Preservatives (same as those of fresh and smoked 
meat) — Heavy metals — Coloring matter (see under 
sausages, etc.) — Fish, salt, dried and oysters — 
Preservatives — Boric acid (same under smoked and 
fresh meat) — Coloring matter — Aniline red and 
cochineal-carmine — In sausages, chopped meat, 
preparations and corned meat — Starch — In sau- 
sages, deviled meat and similar products — Diseased 
meats — Horse-flesh in sausages and in mince-meat. 

Eggs — Test for age. 

CHAPTER III 

Cereal Products 18 

Flour — Adulteration of — Alum — Copper sulfate 

— Substituted flours — General test — Corn meal in 
wheat flour — Wheat flour in rye flour — Ergot in rye 
flour. 

Bread — Adulterations of — Alum — Copper sul- 
fate. 
Ginger Cake — Adulterations of — Stannous chlorid. 



vi CONTENTS 

CHAPTER IV page 

Leavening Materials . 22 

Baking Powders — Flour or starch — Adultera- 
tions of — Tartaric acid (free or combined) — Tartaric 
acid (free) — Phosphoric acid — Sulfates (calcium, 
etc.) — Gypsum — Ammonium salts — Alum. 

Cream of Tartar — Adulterations of — Tartaric acid 
(free or combined) — Aluminium salts — Ammonia — 
Calcium phosphate — Earthy materials — Lime. 

CHAPTER V 

Canned and Bottled Vegetables 27 

Adulterations of — Preservatives — Preparation of 
sample — Formaldehyde — Sulfurous acid and the 
sulfites — Salicylic acid — Saccharin — Benzoic acid 

— Coloring matter — Cochineal — Coal-tar dyes — 
Copper salts — In green pickles, beans, peas, etc. — 
Turmeric — In mixed pickles — Heavy metals (other 
than copper, same as under meats) — Soaked vege- 
tables — Peas, beans and corn — Alum — In pickles 

— Examination of the can or box. 

CHAPTER VI 

Fruits and Fruit Products 36 

Adulterations of — Preservatives — Preparation of 
sample — Salicylic acid — Benzoic acid — Saccharin 

— Coloring matter — Coal-tar dyes — Cochineal — 
Acid magenta — Apple juice in jellies made from small 
fruits — Detection (see test for starch) — Starch — 
In jellies, jams and such products — Gelatin — In 
jellies — Agar agar — Heavy metals — Arsenic. 

CHAPTER VII 

Flavoring Extracts 45 

Lemon Extract — Lemon oil — Citral — Oil of 
citronella — Tartaric or citric acid — Methyl alcohol 

— Coloring matter — Turmeric — Coal-tar colors. 
Vanilla Extract — Adulterations of — Preliminary 

test — Alkali — Foreign resins — Caramel — Tannin 

— Coumarin. 



CONTENTS vii 

CHAPTER VIII page 

Saccharine Products 52 

Honey — Adulterations of — General observations 
— Cane sugar — Commercial glucose syrup — Gelatin. 
Maple Syrup — Adulterations of — General exami- 
nation — Glucose. 

CHAPTER IX 
Spices 54 

Mustard — Adulterations of — Flour — Coloring 
matter — Turmeric — Martius yellow or analogous 
coal-tar coloring matter — Cayenne pepper. 

Pepper — Adulterations of — General test — 
Ground olive stones — Cayenne pepper. 

CHAPTER X 
Vinegar 58 

Adulterations of — Preparation of sample — 
General observations — Cider vinegar — Free mineral 
acids — General tests — Sulfuric acid — Hydrochloric 
acid (free) — Malic acid — Coloring matter — Cara- 
mel — Coal-tar colors — In wine vinegar — Free tar- 
taric acid — In wine vinegar. 

CHAPTER XI 

Fats and Oils 64 

Lard — Adulterations of — Cottonseed oil — Cot- 
tonseed stearin — Beef stearin. 

Olive Oil — Adulterations of — General test — Cot- 
tonseed oil — Peanut oil — Sesame oil — Rape oil. 

CHAPTER XII 

Beverages 69 

Coffee — Adulterations of — General test — Color- 
ing matter — Imitation coffee beans — Chicory. 

Tea — Adulterations of — Foreign leaves — Ex- 
hausted tea leaves — Lie tea — Facing — Catechu. 



PURE FOOD TESTS 

CHAPTER I 
DAIRY PRODUCTS 

MILK 

Milk is adulterated by watering, removing the cream or 
by adding some foreign substance. Formaldehyde, boric 
acid or salicylic acid may be added to preserve the milk. 
Annatto, caramel or some coal-tar dye is added, sometimes 
to improve the color of the milk, and at other times to cover 
up traces of watering. Gelatin and starch are added for 
the same purpose, though they are not frequently used. 
Baking soda is sometimes used to neutralize the acid 
formed in the milk. 

Purity of Milk 

Only lactic acid bacteria should be present in normal 
milk and these produce neither gas nor bad odors. The 
presence of foreign bacteria may be determined by the 
so-called Wisconsin curd test. Heat a pint of the milk 
in a covered jar or bottle to about q8° F. Coagulate the 
milk by adding 10 drops of standard rennet extract and 
thoroughly mixing. Remove the whey. Its removal 
may be facilitated by cutting the curd up into small pieces 
with a knife. Drain off the whey completely until the 
curd is well matted. Immerse the vessel containing the 
curd in warm water, 98 to 102 F., and incubate. Keep 



2 PURE FOOD TESTS 

the vessel closed to retain any odors. After 6 to 9 hours 
open and observe the odor; and by cutting with a sharp 
knife ascertain if it is full of pin holes or gas holes. Again 
note the odor. When this curd is spongy it indicates the 
presence of gas-forming bacteria and hence bad milk. 
Bad odors indicate the same quality of milk. 

Dirt, Hair, etc. 

Insert a plug of clean absorbent cotton in the mouth 
of a funnel from the inside. Filter through this a pint of 
the well mixed milk. Examine the sediment collected 
by the aid of a magnifying glass. 

ARTIFICIAL COLORING MATTER 

Annatto 

Add acid sodium carbonate to a sample of the milk 
until it shows a slight alkaline reaction. Immerse a 
piece of filter-paper and leave it in for 12 or 15 hours. If 
annatto is present, there will be a reddish-yellow stain on 
the paper. 

Caramel 

Leach's Method. — Warm 150 cc. of the sample and add 
5 cc. of acetic acid, then continue heating it nearly to the 
boiling point, stirring while it is being heated. Separate 
the curd by gathering it with the stirring rod or by pouring 
through a sieve. Press out all the whey from the curd and 
macerate the latter for several hours (10 to 12 hours) in 
50 cc. of ether. It is best to do this in a tightly corked 
flask, shaking it frequently. If the milk was uncolored or 



DAIRY PRODUCTS 3 

colored with annatto the curd when thus treated will be 
white. If the curd is a dull brown color caramel was prob- 
ably used to color the milk. Confirm its presence by shak- 
ing a portion of the curd with concentrated hydrochloric 
acid (sp. gr. 1.20) and gently heating. If the acid solution 
turns blue while the curd does not change its color, caramel 
was used to color the milk. (Remember that the ether- 
extracted curd must be brown.) 

Coal-tar Colors 

Lythgoe's Method. — Mix in a porcelain vessel about 
15 cc, each of the sample of milk and hydrochloric acid 
(sp. gr. 1.20) and break up the curd into coarse lumps by 
shaking gently. If an azo-color was used to color the milk 
this curd will be pink, but the curd of normal milk will be 
white or yellowish. 

Starch 

The presence of starch in milk may be detected by 
heating a small quantity of the milk to boiling. When 
it has cooled add a drop of iodin in potassium iodid, and 
if starch is present there will be a blue coloration. 

Gelatin 

A . W. Stokes' Method. — Dissolve 1 part by weight of 
mercury in 2 parts of nitric acid (sp. gr. 1.42). Add 24 
times this volume of water. Mix equal volumes (about 
10 cc.) of this reagent and the milk or cream, shake well 
and add 20 cc. of water. Shake again and, after standing 
5 minutes, filter. When a great quantity of gelatin is pres- 
ent the filtrate will be opalescent instead of perfectly clear. 



4 PURE FOOD TESTS 

To a little of this filtrate in a test tube add the same volume 
of a saturated aqueous solution of picric acid. If much 
gelatin is present a yellow precipitate is produced, smaller 
amounts produce a cloudiness. If the filtrate is perfectly 
clear gelatin is absent and picric acid may be added without 
producing any noticeable effect. 

PRESERVATIVES 

Formaldehyde 

Hehner's Sulfuric Acid Test. — Put 10 cc. of the sus- 
pected milk in a wide test tube and pour carefully down 
the side of the inclined tube about 5 cc. commercial sul- 
furic acid so that it forms a separate layer at the bottom. 
A violet coloration at the union of the two liquids indicates 
the presence of formaldehyde. If the commercial acid is 
not available, the pure acid may be used, but a few drops 
of ferric chlorid must be added. Sometimes the charring 
effect of the acid makes it advisable to use the following 
test: 

Hydrochloric Acid Test. — 2 cc. of 10 per cent ferric 
chlorid is added to one liter of commercial hydrochloric 
acid sp. gr. 1. 2 (or any quantity in this proportion). To 
10 cc. of this mixture add 10 cc. of the milk to be tested. 
Heat the mixture slowly nearly to the boiling point, in an 
evaporating dish, but agitating it all the while to prevent 
the curd collecting in one mass. If formaldehyde is pres- 
ent there will be a violet coloration. It is said that by 
this test as small a quantity of formaldehyde as 1 part in 
250,000 parts of milk can be detected. It is not so 
sensitive in sour milk. 



DAIRY PRODUCTS 



Boric Acid 



Turmeric Paper Test. — Incinerate some of the milk, 
and acidulate the ash with a very few drops of dilute hydro- 
chloric acid and afterwards dissolve it in a few drops of 
water. Place a strip of turmeric paper in this solution for 
a few minutes, then remove and dry it. If boric acid either 
free or combined is present, the turmeric paper will be 
turned to a cherry-red color. 

Another way of making this test. — U. S. Dep. of Agr., 
Div. of Chem., Bui. 65, p. no: Make strongly alkaline 
with lime water, 25 grams of the milk, and evaporate to 
dryness on the water bath. Destroy the organic matter 
by igniting the residue. Dilute with 15 cc. of water and 
acidify with hydrochloric acid. Then add 1 cc. of the 
concentrated acid. Dip a piece of delicate turmeric paper 
in the solution; and if borax or boric acid is present, it 
will have a characteristic red color when dry. Ammonia 
changes it to a dark blue green, but the acid will restore 
the color. 

(Turmeric paper may be prepared by dipping pieces of 
smooth, thin filter paper in a solution of powdered turmeric 
in alcohol.) 

Salicylic Acid 

(This is not often used as a preservative of milk.) 
Leach suggests the following method for its detection. — 
Dissolve one gram of mercury in 2 grams of nitric acid 
(sp. gr. 1.42) and then add to the solution the same volume 
of water. Add 1 cc. of this reagent to 50 cc. of the milk 
to be tested, and shake and filter. The perfectly clear 



6 PURE FOOD TESTS 

filtrate is shaken with ether and the ether extract evap- 
orated to dryness. Then add a drop of ferric chlorid 
solution, and a violet color will be produced if salicylic 
acid is present. 

BUTTER 

Butter is often colored with annatto, saffron, turmeric, 
marigold or coal-tar colors. By a certain process, stale or 
old butter is sometimes worked over and made to appear 
fresh for a time. This is sold under the name of "process" 
or "renovated" butter. Foreign fats like cottonseed oil, 
sesame oil, or oleomargarine may be substituted for or 
added to pure butter. 

COLORING MATTER 

Martin's Test. — Add 2 parts of carbon bisulfid, a little 
at a time and with frequent shaking, to 15 parts of alcohol. 
Shake 25 cc. of this solution with 5 grams of the butter, 
and let stand for some time. The carbon bisulfid dissolves 
out the fatty matter and settles to the bottom. The 
alcohol remains on top and will dissolve out any artificial 
colors that may be present. If only a little coloring matter 
is present use more of the butter. 

Annatto 

Evaporate a portion of the extract to dryness and add 
sulfuric acid to the residue. If annatto is present a green- 
ish-blue color forms. Should a pink tint result the 
presence of a coal-tar color is to be suspected. 



DAIRY PRODUCTS 



Coal-tar Colors 



These colors will dye wool or silk if pieces of the fiber are 
boiled in the diluted alcoholic extract, which has first been 
acidified with hydrochloric acid. The normal butter color- 
ing matter will not dissolve when thus treated. 

Geisler's Method. — To a few drops of the clarified fat on 
a porcelain surface, add a very little fuller's earth. If a 
pink to violet-red coloration is produced in a short time 
the presence of an azo-color is indicated. 

Saffron 

When saffron is present, nitric acid colors the alcoholic 
extract green, and hydrochloric acid colors it red. 

Turmeric 

Add ammonia to the alcoholic extract, and if it turns 
brown it indicates the presence of turmeric. 

Marigold 

Add silver nitrate to the extract, and if it turns black 
the presence of marigold is indicated. 

Process or Renovated Butter 

Heat a little of the suspected butter in a spoon or dish, 
and if it is process butter it will sputter, but not foam 
much. Make the test also with some butter known to be 
pure and fresh. 

Hess and Doolittle Test. — Melt some of the butter (say 



8 PURE FOOD TESTS 

40 grams) at about 50 C. If the butter is pure and fresh 
the melted fat will clear up almost as soon as it is melted, 
while the fat of process butter remains turbid for quite 
a while. After most of the curd has settled, decant as 
much as possible of the fat. Pour the remainder on a 
wet filter. Add a few drops of acetic acid to the water 
that runs through from the filter, and boil. If it was 
ordinary butter this filtrate will become milky, but if 
process butter a flocculent precipitate will form. 



Oleomargarine 

Immerse a test tube containing some of the filtered fat 
in boiling water for 2 minutes. Make a mixture of 1 part 
glacial acetic acid, 6 parts ether, and 4 parts alcohol. 
Add to 20 cc. of this mixture in a 50 cc. test tube, 1 cc. of 
the heated fat, which may be transferred by means of a hot 
pipette. Stopper the tube and shake it well. Immerse 
in water at 15 or 16 C. Pure butter when thus treated 
remains clear for quite a while. There will be only a very 
little deposit after standing an hour, but oleomargarine 
gives a deposit almost immediately, and in a few minutes 
there will be a copious precipitate. 

When the oleomargarine in butter is in about the pro- 
portion of 1:10, it will not separate much short of 15 
minutes. 

"Milk" Test. —Add a spoonful of butter to 60 cc. of 
sweet milk in a wide-mouth bottle setting in boiling water. 
Stir until the fat is melted. Then place the bottle in 
ice water and stir the fat till it solidifies. Either fresh or 
renovated butter will solidify in a granular mass distributed 



DAIRY PRODUCTS g 

throughout the milk in finely divided particles. Oleo- 
margarine will solidify in one chunk which may be lifted 
out with the stirrer. 

Cottonseed Oil 

The presence of this oil may be detected by Halpen's 
test, which is given under lard, page 64. 



CHAPTER II 

MEATS AND EGGS 

Meats are preserved by treating them with potassium 
nitrate, boric acid, sulfurous acid, salicylic acid, or benzoic 
acid. Cheap meat may be substituted for the more ex- 
pensive. A few cases of horse meat in mince meat and 
sausages have been discovered. Diseased and stale meats 
have been found on the market. Canned meats often con- 
tain zinc, tin, and lead, and sometimes even arsenic. Ani- 
line-red or cochineal-carmine may be added to improve the 
color of chopped or ground meats. Starch is sometimes 
added to sausage and similar meat. Fish and oysters may 
be preserved with boric acid or borax. 

FRESH AND SMOKED PRODUCTS — PRESERV- 
ATIVES 

Potassium Nitrate (Saltpeter) 

Corned and smoked meats are usually preserved with 
saltpeter. Since smoked and cured meats are used in 
making potted meats, saltpeter is quite frequently found in 
the latter. It may be detected by the usual test for nitrates 
since no other nitrate is apt to be present, though one may 
identify the metal by the qualitative test for potassium. 

To test for nitrates treat a little of the meat with 2 or 3 cc. 
of a 1 per cent solution of diphenylamine in strong sulfuric 



MEATS ii 

acid. If a nitrate is present a deep blue color forms in- 
stantly, which is not obscured by the charring effect of the 
acid. 

Boric Acid 

Pick apart into fine pieces about 25 or 50 grams of the 
lean meat and warm with a little water which has a few drops 
of hydrochloric acid in it. Soak a piece of turmeric paper 
in the extract, and if boric acid is present the paper will be 
colored rose-red when it is dry. A weak alkali turns this 
colored paper olive. 

Another method is to burn a piece of the meat to an ash, 
after being treated with lime water. Make a solution of 
the ash and make slightly acid with hydrochloric acid. 
Then test with the turmeric paper with the same results as 
in the above method. 

Sulfurous Acid 

U. S. Dep. Agr., Bureau Chem., Bui. 107, pp. 113, 187: 
Digest 40 or 50 grams of the meat in hot water, treat with 
10 cc. glacial phosphoric acid to coagulate the proteids. 
Strain through a cotton bag and transfer the filtrate to a 
short-necked flask and distil receiving the first part of the 
distillate in a solution of iodin. Boil, and add barium 
chloride. If sulfurous acid is present, it will be oxidized 
to sulfuric acid and precipitated as barium sulfate by the 
barium chlorid. More than a mere trace of the precipitate 
proves that some sulfite was used to preserve the meat. 

Another method suggested by Kammerer is to place the 
meat on paper, which has been saturated with potassium 
iodate moistened with dilute sulfuric acid (1:8); nitric oxid 
must not be present. If sulfurous acid is present a deep 



12 PURE FOOD TESTS 

blue color forms at once. A trace of this color may form 
after some time with meat that is not fresh, hence this 
method cannot be used in examining canned meat. 

Salicylic Acid 

Heat 50 grams of the meat in 50 cc. of water. Add 10 cc. 
of a strong solution of glacial phosphoric acid and strain 
through a cotton bag. Extract the filtrate with a little 
ether (about 50 cc.) in a separatory funnel. Let the ether 
evaporate spontaneously. Take up the residue with 3 cc. 
of water, and add one or two drops of a one-half per cent 
solution of ferric chlorid. If salicylic acid is present the 
mixture will be purple or violet. 

Leach makes the same test by slightly acidifying a por- 
tion of the lean meat, then extracting with ether, and evap- 
porating to dryness and testing the residue with a drop of 
ferric chlorid solution. A deep violet coloration is pro- 
duced if salicylic acid is present. 

Benzoic Acid 

Mohler's Method. — Prepare a sample as in the test for 
salicylic acid by heating 50 grams of the meat in 50 cc. of 
water. Add 10 cc. of a concentrated solution of glacial 
phosphoric acid, and strain through a cotton bag. Neu- 
tralize with sodium hydrate and evaporate to dryness or to 
a small volume. After treating with 3 cc. of concentrated 
sulfuric acid, heat till white fumes appear. Add 4 or 5 crys- 
tals of potassium nitrate and continue heating until the solu- 
tion is colorless or nearly so. When cool dilute with water, 
add an excess of ammonia, and place in a narrow vessel like 
a test tube. Add one or two drops of ammonium sulfid 
carefully so that the liquids do not mix. If the surface of 



MEATS 13 

the liquid immediately becomes red, benzoic acid is 
present. 

If this test is not carefully performed, it is worthless, as 
other substances give similar results. 

Confirm its presence by neutralizing the aqueous solution 
of the extracted benzoic acid with sodium hydroxid; con- 
centrate to a very small volume. Acidify with sulfuric 
acid. A white flocculent precipitate shows the presence of 
considerable benzoic acid. 

CANNED MEAT 

If in preparing canned meat only fresh meat is used, there 
is little need for the use of preservatives, but as considerable 
smoked and cured meat is thus used, preservatives may 
find their way into canned meat. 

The same preservatives should be looked for as in fresh 
and smoked meat and the same test made for each. 

Heavy Metals 

A. H. Allen's Method. — About 25 grams of the substance 
is mixed slowly with enough strong, pure sulfuric acid to 
just moisten the mass, avoiding an excess. Heat on a 
water-bath for a short time, then raise the temperature 
gradually, and maintain till the chlorids seem to be decom- 
posed. It must not be hot enough, however, to volatilize 
the sulfuric acid. Then add 1 cc. of strong nitric acid and 
heat till red fumes are given off. Freshly ignited magnesia 
in the proportion of 0.5 gram for each cc. of sulfuric and 
nitric acid previously used is now stirred into the mass and 
the whole ignited at a dull red heat. This is best done in a 
gas-muffle. When cool, moisten the ash with nitric acid 
and gently re-ignite, repeating this treatment till the carbon 



14 



PURE FOOD TESTS 



is entirely consumed. Treat the residue with 8 or 10 drops 
of strong sulfuric acid, heat till fumes are given off, cool, 
boil with water, dilute to about ioo cc. and saturate with 
hydrogen sulfid, filter, examine as follows: 



Zinc and iron may be 
in solution. Add bromine 
water to destroy hydrogen 
sulfid and to oxidize the 
iron, boil and add am- 
monium hydrate in excess, 
boil again and filter. 


Lead, tin, copper, and calcium, if 
present, will be in the precipitate and 
residue. Fuse the mass in a porcelain 
crucible for at least ten minutes with 
2 grams each of potassium and sodium 
carbonates and half as much sulfur. 
After cooling, boil with water and filter. 


The precipi- 
tate will contain 
the iron and the 
phosphates. 


Filtrate, when 
blue, proves the 
presence of 
nickel. 


Residue. Add hydrochlo- 
ric acid and boil as long as 
hydrogen sulfid is given off. 
A few drops of bromine 
water will complete the oxi- 
dation of the copper sulfid. 
Filter, and add ammonium 
hydroxid in excess to the fil- 
trate. When the filtrate is 
blue, it indicates the pres- 
ence of copper. Acidify the 
filtrate with acetic acid and 
test for lead by adding po- 
tassium chromate, a yellow 
precipitate being formed 
when it is present. 


The filtrate 
may contain tin. 
Acidify with 
acetic acid, and 
if tin is present 
a yellow pre- 
cipitate of stan- 
nic sulfid will 
form. 




I. Heat to 
boiling and add 
potassium fer- 
rocyanid. A 
white precipi- 
tate or turbidity 
indicates zinc. 







MEATS 15 

FISH SALT DRIED AND OYSTERS 

This kind of meat is often preserved with boric acid and 
borax. They may be detected by the method given under 
fresh and smoked meat. 

COLORING MATTER 

Sausages and other chopped meat preparations, together 
with corned meat that has been cured without saltpeter, 
are often treated with artificial coloring matter. 

Aniline red and cochineal carmine are usually employed 
for this purpose. The former may be detected, according 
to Allen, by picking the meat apart and treating it with 
methylated spirit, strain or filter the extract and take up 
with water. Then a piece of white wool (nun's veiling will 
do) is immersed in the boiling liquid and, if it is dyed red, 
rosaniline is present. 

Cochineal-carmine may be detected by the method used 
by Klinger and Bujard. Cut up fine about 20 grams of 
the meat and heat in a water-bath with water and glycerine 
mixed in equal parts. If the above coloring matter is 
present the liquid will become quite red in color, if not 
present a slight yellow color results from this treatment. 
If a spectroscope is available this dye is easily recognized. 

STARCH 

In Sausage, Deviled Meat, and Similar Products 
Cracker and bread crumbs are often added to these 
preparations and their presence is best detected by examin- 
ing the amount of starch present. Do this by boiling some 
of the sample in water, and when cool adding a drop or two 
of iodin reagent. The usual blue color is produced if much 



16 PURE FOOD TESTS 

starch is present. If there is only a little starch, it may be 
necessary to examine it under the microscope to determine 
whether the starch is from the pepper and other spices used 
or from some cereal. 

DISEASED MEAT 

The following method is recommended by Ebers. — Hold a 
small piece of the suspected meat over a mixture of i cc. 
hydrochloric acid, 3 cc. alcohol, and 1 cc. of ether. The 
formation of ammonium chlorid fumes shows that decom- 
position has begun. Do not mistake the fumes of the acid 
for those of ammonium chlorid. 

HORSE FLESH 
In Sausage and Mince Meat 

This sophistication is not common in this country. Horse 
flesh is detected by testing for glycogen, which is present in 
it in larger quantities than in other meats. 

Courley 6° Coremon's Test. — Boil 50 grams of the meat 
for a half hour with water, strain, and to a portion of the 
filtrate add a few drops of potassium iodid-iodin solution 
(potassium iodid 0.4 gram; iodin 0.1 gram; water 20 cc). 
If considerable horse meat is present the glycogen will color 
the liquid dark brown, which disappears on heating, but 
returns on cooling. 

EGGS 

It sometimes happens that one wishes to know the age of 
eggs without opening them. 

Delarne's Test. — Place the egg in a 10 per cent solution 
of common salt. Perfectly fresh eggs sink to the bottom. 



MEATS 17 

Those remaining immersed, but suspended in the liquid, are 
at least three days old, while those rising to the surface and 
floating are more than five days old. The older the egg, 
the higher it floats and the more it will stand on end. This 
test is not applicable to eggs that have been preserved. 

Hold the egg between a bright light and the eye, and if 
the air chamber is small, and no dark spots but instead a 
rather uniform rose-colored tint is seen, the egg is fresh. 
If the contents appear cloudy and the air chamber larger, 
the egg is not fresh. The darker the contents of the egg 
the older it is. 



CHAPTER III 
CEREAL PRODUCTS 

FLOUR 

Sometimes a cheaper or inferior grade of flour is sub- 
stituted for one of higher quality, and even a different kind 
of flour may be substituted, as corn meal in wheat flour, or 
wheat in rye flour. Alum may be added by millers to 
cover up traces of bad flour, and by bakers to make the 
bread white when a bad or cheap flour is being used. 
Copper sulfate also may be added to improve the appear- 
ance. Occasionally rye flour is made from rye upon which 
ergot has developed. Stannous chlorid and potassium 
carbonate are added to ginger cake to give the same color 
to the product made of molasses and a poor grade of flour 
as that made from good flour and honey. 

ALUM 

Wynther Blyth Method. — Add a little water to the 
sample and macerate. Soak pieces of gelatin in the solu- 
tion and leave for a half day, remove the gelatin and dip 
the pieces in a mixture of equal volumes of a fresh tincture 
of logwood and a saturated solution of ammonium car- 
bonate. The gelatin strips will turn blue if alum is present. 

Bell & Carter Method. — Make a fresh 5 per cent tinc- 
ture of logwood in methyl alcohol. Dampen about 10 
grams of the flour with water and add 1 cc. of the logwood 
tincture and the same quantity of a saturated solution of 
ammonium carbonate. Pure flour gives a pinkish color 
which fades to buff or brown. The presence of alum 

18 



CEREAL PRODUCTS 19 

produces a lavender or bluish tint which becomes more 
distinct as it dries. 

COPPER SULFATE 

This adulterant may be detected in either flour or 
bread, by soaking the flour or bread in a dilute solution of 
potassium ferrocyanid acidulated with acetic acid. If 
copper be present a purplish or reddish-brown coloration 
will be produced. 

SUBSTITUTED FLOURS 

Examine the flour under the microscope and compare 
with a sample known to be pure. Any adulteration of 
the flour by substituting another flour may be determined 
by comparison with pure samples of the different flours. 

VogeVs Method. — Make a mixture of alcohol (70 per 
cent) 95 parts, hydrochloric acid 5 parts. Treat a sample 
of the flour in a test tube with this reagent. Shake well. 
Heat to boiling and allow to settle. A colorless fluid 
shows the flour to be pure, a straw-colored tint indicates 
the presence of gruffs with bran, an orange-yellow proves 
the presence of corn-cockle flour, a flesh-colored liquid 
indicates the presence of ergot, while a green color indicates 
buckwheat flour. 

Corn Meal in Wheat Flour 

Kraemer claims to be able to detect as small amount as 5 
per cent of maize in wheat flour, by the following test. — Mix 
a gram of the flour with 15 cc. of good glycerin, and heat to 
boiling for a short time. If corn meal is present, there will 
be an odor like that of pop corn. 



20 PURE FOOD TESTS 

Wheat in Rye Flour 

Kleeburg recommends the following test. — A little of the 
flour is mixed on a piece of common window glass or micro- 
scope slide, with sufficient water (at 45 C.) to float the 
flour particles. Spread the mixture out over the glass, and 
press another glass down upon it. When wheat flour is 
present, white spots will be seen, and if the glasses are slid 
upon each other the spots will pull out into threads, and 
the thicker and longer they are the more wheat flour there 
is present. 

Ergot in Rye Flour 

Boettger gives the following chemical test for ergot. — Heat 
10 to 15 minutes with an equal quantity of ether, adding a 
few crystals of oxalic acid. When ergot is present a red- 
dish color develops. 

Another Method. — Bui. 51, Bureau of Chem. 

Digest 20 grams of the suspected flour, with boiling 
alcohol, till no more color is extracted. Add 1 cc. of sul- 
furic acid (1:3), and if ergot is present the solution will be 
colored red. 

BREAD 

ALUM 

Moisten a piece of the bread with water, and then with a 
logwood solution (5 grams logwood digested in 100 cc. of 
alcohol). If alum is present the bread will become laven- 
der blue in two or three hours. Pure bread would have a 
red-brown tint. To prove the presence of alum, the blue 
color must be permanent at the temperature of boiling 
water. (The logwood used in this test must be pure.) 



CEREAL PRODUCTS 21 

Blyth's Test. — Macerate 150 grams of the sample for 
45 or 50 hours in a couple liters of water; after straining 
through muslin, evaporate to a small volume over a low 
flame. Immerse a strip of gelatin in this liquid, and then 
in a logwood solution (same as in last test), and if alum is 
present it will acquire the lavender color. 

If the bread in either of these tests is sour, the following 
modification (Vanderplanken) must be made. Reduce 15 
grams of the sample to a paste with water and some pure 
chlorid of sodium, adding 10 drops of a fresh alcoholic 
solution of logwood, after which add 5 grams of pure potas- 
sium carbonate. Mix well, and after washing with 100 cc. 
of water into a vessel allow to settle. If alum is present 
the liquid will soon become reddish-violet, and if not present 
it will be blue. 

COPPER SULFATE 

See Test for Copper Sulfate in Flour 

GINGER CAKE 

Tin may be detected by the method for heavy metals 
under meat. 



CHAPTER IV 

LEAVENING MATERIALS 

BAKING POWDERS 

Baking powders consist of bicarbonate of soda and an 
acidifying agent as acid potassium tartrate, acid calcium 
phosphate, tartaric acid or alum. Starch is generally 
added as a "filler," the object being to prevent the in- 
gredients acting too soon. Some powders contain both 
acid calcium phosphate and alum. The kind of powder 
is determined by testing for these. Gypsum has been 
added to baking powders to increase the weight. 

FLOUR OR STARCH 

Add to a small portion of the sample a few drops of 
tincture of iodin (made by dissolving iodin in alcohol). 
A blue coloration indicates the presence of starch. 

TARTARIC ACID 

Free or Combined 

Wolf's Method. — If no starch is present, mix a little of 
the powder with some dry resorcin. Add a few drops of 
sulfuric acid and heat gently. A rose-red color forms if 
tartaric acid or tartrates are present. The color should 



LEAVENING MATERIALS 23 

disappear when diluted with water. When starch is 
present, mix well by shaking about 5 grams of the powder 
with 250 cc. of cold water. Let the insoluble matter 
settle and pour the liquid upon a filter. Evaporate the 
nitrate to dryness, treat the powdered residue with a few 
drops of a 1 per cent solution of resorcin. Add 3 cc. of 
strong sulfuric acid, heat slowly. A rose-red color forms 
if tartaric acid is present. The color should be destroyed 
on the addition of water. This test is applicable in the 
presence of phosphates and the acid may be free or com- 
bined. 

TARTARIC ACID 

Free 

Make an absolute alcoholic extract of 5 grams of the 
powder and evaporate the alcohol. Add sufficient dilute 
ammonia to dissolve the residue, place in a test tube and 
drop in a crystal or two of silver nitrate. Heat gently, 
and a silver mirror will form if tartaric acid is present. 



PHOSPHORIC ACID 

Place 5 grams of the sample in a porcelain dish and 
ignite. Add nitric acid to the residue, heat for a short 
time, dilute and filter. Add a solution of ammonium 
molybdate, warm slightly. If phosphoric acid is present 
a copious yellow precipitate of ammonium phosphomolyb- 
date will form. Do not be deceived by the slight precipi- 
tate which always forms if flour is present, since the ash 
of flour always contains a little calcium phosphate. 



24 PURE FOOD TESTS 

SULFATES 

Calcium, etc. 

Boil a portion of the sample gently with strong hydro- 
chloric acid, add barium chlorid. A white precipitate of 
barium sulfate will form if sulfuric acid is present. 

GYPSUM 

Calcium Sulfate 

Ash a portion of the sample and make the usual quali- 
tative tests for calcium sulfate. 

AMMONIUM SALTS 

Extract a few grams of the sample with cold water, 
boil the extract with sodium hydroxid and place a piece of 
moist red litmus paper in the steam. It will be colored 
blue if ammonia is present. 

ALUM 

Reduce to an ash about 2 grams of the powder in a 
platinum dish. Extract with boiling water, add am- 
monium chlorid solution to the filtrate until a distinct 
odor of ammonia is given off. 

If a flocculent precipitate forms it indicates the presence 
of alum. 

This test for alum is applicable in the presence of 
phosphates. 

Mrs. Richards. — Cover some logwood chips (they must 
be pure) with water and bring to a boil. Repeat this four 



LEAVENING MATERIALS 25 

times, saving only the last decoction. Shake some of the 
sample (a couple of teaspoonfuls) in a beaker half full of 
water. When it ceases effervescing, strongly acidify with 
acetic acid. Add a few drops of the logwood extract, and 
if alum is present a bluish-red color will appear. 



CREAM OF TARTAR 

Cream of tartar is bitartrate of potassium and is ob- 
tained from the lees deposited in wine casks. If gypsum 
has been used to clarify the wine, it will be present in the 
cream of tartar as calcium tartrate. 

Other adulterants of cream of tartar are acid calcium 
phosphate, starch, gypsum and alum. 

TARTARIC ACID 

Free or Combined 

If the sample is known to be free from starch the follow- 
ing test may be made: 

Mix a bit of the powder with a small quantity of dry 
resorcin and add a few drops of concentrated sulfuric acid. 
Heat slowly, and if a rose-red color forms, which disap- 
pears when diluted with water, there is present either 
tartaric acid or a tartrate. 

When the sample contains starch, shake about 4 or 5 
grams of it a number of times with 250 cc. of cold water 
in a large flask. Pour on a filter after the insoluble ma- 
terial has settled and evaporate the filtrate to dryness. 
The residue is to be tested for tartaric acid and tartrates, 
the same as when starch was absent. 



26 PURE FOOD TESTS 

ALUMINIUM SALTS 

Mix equal quantities (about i gram) of the sample and 
sodium carbonate and burn to an ash. Extract with 
boiling water and filter. Add to this filtrate enough 
ammonium chlorid solution to cause a distinct evolution 
of ammonia. The formation of a flocculent precipitate 
shows the presence of aluminium. This test may be used 
when phosphates are present. 

AMMONIA 

Present in the Form of Ammonium Alum or Ammonium 
Carbonate 

Make a cold water extract of the powder and boil it 
with sodium hydroxid. Test the steam with moist red 
litmus paper. 

CALCIUM PHOSPHATE 

Ignite a sample of the cream of tartar and test the 
same as for phosphoric acid under baking powders. 

EARTHY MATERIALS 

Treat the sample with warm potassium hydroxid. A 
residue indicates some earthy material. 

LIME 

When phosphates are absent ignite the sample and 
dissolve the residue in distilled water, slightly acidified 
with hydrochloric acid, filter, add a few drops of am- 
monium oxalate and an excess of ammonium hydroxid. 
A white precipitate indicates the presence of lime. 



CHAPTER V 

CANNED AND BOTTLED VEGETABLES 

No class of foods on the market has less need for anti- 
septics than canned goods, yet their use is rather common. 
Products thus treated are easier canned and are not so apt 
to spoil. The chemicals used as preservatives are sulfurous 
acid, and the sulfites, salicylic acid and saccharin, benzoic 
acid, and sometimes formaldehyde. Sulfurous acid is 
used to bleach such foods as canned corn. Saccharin 
possesses some antiseptic properties, but its main use is as 
a sweetener. Alum is used to make pickles hard and crisp. 

Some canned or bottled goods, as tomato-catsup, is col- 
ored with cochineal or coal-tar dyes. Green pickles, beans, 
peas, and such vegetables are colored by copper salts or 
are cooked in copper vessels, with the addition of acetic 
acid, hence the beautiful green color. Turmeric is some- 
times used to color mixed pickles. 

The heavy metals as lead, zinc, and tin are generally 
present in canned goods, the amount varying with the cor- 
rosive power of the vegetable. 

When there is a year of scarcity in corn, peas, beans, and 
such vegetables, the dried product is often soaked and 
canned. Some of this goods is sold for the regular green 
vegetable, while some may be properly marked "Soaked 
Goods." 

27 



28 PURE FOOD TESTS 



PRESERVATIVES 



It is best to make a systematic examination for the differ- 
ent preservatives. The sample may be prepared by mixing 
50 grams of the pulped material with sufficient water in a 
250 cc. graduated flask. Add phosphoric acid till distinctly 
acid in reaction. Fill to the mark with water. Place in a 
distilling flask, and distil in a linseed oil or a paraffin bath 
till 30 cc. have been collected. Save this distillate for the 
following tests. 

Formaldehyde 

To 5 cc. of the above distillate in a test tube, add 2 or 3 
drops of a 1 per cent aqueous solution of phenol and mix 
well. Incline the tube and carefully pour down the side 
5 cc. of concentrated commercial sulfuric acid so that the 
two liquids do not mix. If formaldehyde is present there 
will be a crimson zone at the plane of union of the solutions. 
This coloration takes place when the formaldehyde is 
present in the proportion of 1 part in 100,000 parts. When 
there is a greater quantity of formaldehyde present a white 
turbidity or a light-colored precipitate forms above the 
coloring. 

Phenylhydrazine Hydrochloric Test. — Dissolve 2 grams 
of phenylhydrazine hydrochlorid and 3 grams of sodium 
acetate in 20 cc. of water. Add 2 to 4 drops of this reagent 
and the same number of drops of sulfuric acid to 1 or 2 
cc. of the above distillate, to be examined in a test tube. A 
green coloration is produced when formaldehyde is present. 

Hydrochloric Acid Test. — Add 5 cc. of the distillate to 
be tested to about 5 cc. of milk known to be pure, and about 
10 cc. of concentrated hydrochloric acid (sp. gr. 1.2) which 
contains 1 cc. of a 10 per cent ferric chlorid solution to each 



CANNED AND BOTTLED VEGETABLES 29 

500 cc. of the acid. Heat slowly to 8o° or 90 C. over the 
free flame, agitating it at the same time to break up the 
curd. A violet coloration indicates formaldehyde. 

Sulfurous Acid and the Sulfites 

Free sulfurous acid is not largely used as a food pre- 
servative, though its salts are quite commonly employed. 

Detection. — Mix 150 grams of the finely ground sample 
with enough water to make a thin paste. Acidify with 
phosphoric acid and distil till 25 cc. have been collected. 
(The delivery tube of the condenser should dip below the 
surface of a little water.) Treat the distillate with a few 
drops of bromine water and boil for a short time. If a 
precipitate forms on the addition of barium chlorid the 
presence of sulfurous acid is indicated. 

Salicylic Acid 

Acidify 50 cc. of the sample with sulfuric acid, and shake 
vigorously with 50 cc. of a mixture of equal parts of ether 
and petroleum spirit. When the liquids have separated, 
draw off as much as possible of the solvent and filter. If 
an emulsion forms use a centrifugal machine, and evaporate 
with a small flame. If needle-shaped crystals form, sali- 
cylic acid is present. Add a few drops of water and a drop 
of very dilute ferric chlorid solution in such a way that the 
solutions will come together slowly. The presence of 
salicylic acid gives a purple or violet color. 

Saccharin 

This is used quite extensively as a sweetening agent in 
canned sweet corn, and other similar products. 

Macerate about 20 grams of the sample after mixing with 



3 o PURE FOOD TESTS 

30 to 40 cc. of water and strain through muslin. Acidify 
with 1 or 2 cc. of sulfuric acid (1 to 3) and extract with 
ether. (If an emulsion forms, use a centrifugal machine.) 
Separate the ether layer and let the ether evaporate spon- 
taneously and use the residue in the following tests: 

Take up a part of the residue with water and taste. If it 
is very sweet saccharin is present. Confirm by the following : 

Schmidt } s Test. — Add about 1 gram of sodium hydroxide 
to another part of the residue, and heat in an air-oven or 
oil bath, for half an hour at about 250 C, to convert the 
saccharin into salicylic acid. After it has cooled, acidify 
with sulfuric acid, extract and test for salicylic acid with 
2 or 3 drops of ferric chlorid solution, letting the solutions 
come together slowly. A purple or violet coloration proves 
the presence of salicylic acid, which in turn indicates the 
presence of saccharin. This test cannot be used if salicylic 
acid was used as a preservative in the original product. A 
test for the acid should first be made. 

Bomsteirfs Test. — Heat the remainder of the above 
ether residue with resorcin and a very little sulfuric acid till 
it begins to swell. (It is best to do this heating in a test- 
tube.) Let cool till the action stops, heat again and repeat 
the operation several times. After cooling the last 
time, dilute with water and add sodium hydrate till 
neutral. If saccharin is present, there will be a red-green 
fluorescence. 

Benzoic Acid 

Acidify 50 cc. of the sample with sulfuric acid and shake 
vigorously with 50 cc. of a mixture of equal parts of ether 
and petroleum spirit. Let the liquids separate, then draw 
off as much as possible of the solvent and filter. (Use a 



CANNED AND BOTTLED VEGETABLES 31 

centrifugal machine if an emulsion forms.) Separate the 
extract into 2 parts and evaporate each to dryness over a 
small flame and make the following tests: 

Ferric Chlorid Test. — Dissolve one of these residues in 
ammonia, and evaporate to dryness on a water-bath. Take 
up the residue with warm water, filter, and collect the filtrate 
in a small test tube. Add a drop of ferric chlorid solution, 
and if benzoic acid is present a characteristic flesh or brown- 
ish colored precipitate of ferric benzoate forms. Some- 
times in such products as sweet pickles, a basic ferric acetate 
precipitate comes down and the following test had better 
be applied. 

Peter's Method. — Take about 0.1 gram of the second 
part of the above ether residue, place in a large test tube 
(about 50 cc.) and dissolve in 5 to 8 cc. of concentrated 
sulfuric acid. Add from 0.5 to 0.8 gram of barium peroxide, 
a little at a time. Shake each time and cool in water if 
necessary. This should produce a permanent froth on 
the sulfuric acid. Let stand 25 or 30 minutes, then fill the 
tube three fourths full of water, shake and cool rapidly to 
the temperature of the room, and filter off the barium 
sulfate. Extract with chloroform or ether. Remove the 
extract and test it for salicylic acid with dilute ferric chlorid. 
(See first test under salicylic acid.) In this method sali- 
cylic acid must first be proven absent. 

Mohler's Test. — Treat the remainder of the second part 
of the above ether residue with 2 or 3 cc. of concentrated 
sulfuric acid. Heat till white fumes appear. Add a few 
crystals of potassium nitrate and when cool dilute with 
water. Add an excess of ammonia, then a drop or two of 
ammonium sulfid. If a red color appears immediately 
on the surface, it shows the presence of benzoic acid. 



32 PURE FOOD TESTS 

COLORING MATTER IN CATSUPS AND 
TOMATOES 

Cochineal 

Girard and Dupre Test. — Shake well a portion of the 
sample with water and filter, acidify with hydrochloric acid, 
then extract with amyl alcohol, and if cochineal is present 
the extract will be colored yellow or orange, the particular 
shade depending on the amount of cochineal present. 
Remove the amyl alcohol and wash with water until it is 
neutral. To half of this, add a very dilute solution of 
uranium acetate, drop by drop, and shaking well after the 
addition of each drop. Cochineal, if present, will produce 
a characteristic emerald-green color. 

Confirm by adding a drop or two of ammonia to the 
second half of the amyl alcohol extract and a violet colora- 
tion will be produced if cochineal is present. 

Coal-Tar Coloring Matter 

Sostegni and Carpentieri Test. — Free from grease a 
piece of woolen cloth (nun's veiling will do) by boiling first 
in very dilute caustic soda solution and then in water. 
Acidify a portion of the sample with 2 to 4 cc. of 10 per 
cent solution of hydrochloric acid and filter. Strips of the 
cleansed cloth are boiled in this filtrate for 5 or 10 minutes, 
then removed, washed in water and boiled with very dilute 
hydrochloric acid solution. Wash out the acid and dis- 
solve the color from the cloth by boiling in a solution of 
ammonium hydroxid (1 to 50). (The time required will 
depend upon the dye present.) Remove the cloth from 
the solution and acidify the latter with hydrochloric acid 
and another piece of the cleansed cloth is immersed and 



CANNED AND BOTTLED VEGETABLES 33 

again boiled. This second dyeing fixes only coal-tar colors 
on the cloth, hence, no fear of mistaking them for the natural 
color of the vegetable. 

IN GREEN PICKLES, BEANS, PEAS, ETC 

Copper Salts 

Burn 20 grams of the sample to an ash and wet the ash 
with concentrated nitric acid, dilute with water and boil. 
Add ammonia till strongly alkaline and filter. If the 
filtrate is blue, copper is present. 

Confirm by acidifying the filtrate with acetic acid and 
adding potassium ferrocyanid. A red or brownish pre- 
cipitate or coloration proves the presence of copper. The 
test for other heavy metals may be made by the general 
method given under meats. 

IN MIXED PICKLES 

Turmeric 

Shake with alcohol to extract the color. Soak a piece of 
filter p per in the extract and dry in an air oven at ioo° C. 
Wet the filter paper with a weak solution of boric acid to 
which a very little hydrochloric acid has been added. If 
turmeric is present, a cherry- red color will appear when the 
filter paper is dry. 

"SOAKED" VEGETABLES 

Peas, Beans, axd Corn 

There is really no chemical test for this class of foods. 
Certain helpful directions given in Bui. 65, p. 54, of the 
Bureau of Chem., will assist in identifying such goods. 



34 PURE FOOD TESTS 

All or nearly all of the green color of peas and beans is 
destroyed by the process of " soaking." They have the 
appearance of the well-matured product, and are firm and 
mealy with well-formed cotyledons. The process of soak- 
ing starts the growth of the caulicle of the pea. The kernel 
of corn is plump and hard and does not have the milky 
consistency of the immatured product. The characteristic 
succulence of the green pea, bean, and corn is absent in the 
soaked product. 

Alum in Pickles 

This is sometimes added to the pickling solution to pro- 
duce hardness and crispness. 

Burn to ash a sample of the pickles, and, if they are free 
from copper, fuse in a platinum dish with sodium car- 
bonate. Extract with boiling water, and after filtering 
add ammonium chlorid solution. If alum is present, a 
flocculent precipitate will form. 

Examination of the Can or Box in which Vegetables 
are Sealed 

Generally when the ends of a can are convex, instead of 
plane or concave, it is spoiled. In the souring of canned 
sweet corn, it is exceptional that the ends are forced outward. 

Strike the can and the spoiled cans will give a dull sound 
while the good ones will give a distinct tone. Some prac- 
tice will be necessary to use this test. 

One can judge of the amount of tin dissolved by the 
corrosion of the inside of the can. 

Reject cans that show much rust around the cap on the 
inside of the head. 



CANNED AND BOTTLED VEGETABLES 35 

If more than one hole is found soldered in the cap, reject 
the can. Cans of salmon are the only exception that has 
come to the author's notice. A second hole, in general, 
indicates that decomposition had set in and the can had 
been punctured and resealed. 



CHAPTER VI 

FRUITS AND FRUIT PRODUCTS 

Salicylic acid, benzoic acid, and saccharin are used to 
preserve fruits. The last is also added as a sweetener 
instead of sugar. Many fruit products lose their color 
with age, and to give them a lasting color they are treated 
with a coal-tar dye, cochineal, acid magenta, or caramel. 

A very small per cent of the jams and jellies sold are 
strictly pure. These cheap products are made up prin- 
cipally of apple juice and commercial glucose; artificial 
essences are added to imitate the real flavor. 

In cheap jellies made of apple juice and glucose syrup, 
a " coagulator " is used; usually sulfuric acid and alum, 
also citric and tartaric acids may be used for this purpose. 

Starch, gelatin, and agar are used as gelatinizing agents. 

Fruits put up in tin cans may dissolve the heavy metals 
as tin, zinc, lead, and even arsenic. 

PRESERVATIVES 

Preparation of the Sample. — Dissolve 25 or 30 grams of 
the sample in water which has been acidified with sulfuric 
acid (1 to 3), then extract with ether, and remove the ether 
layer and let it evaporate spontaneously. The residue 
may contain salicylic acid, benzoic acid, or saccharin. Take 
up with a little water and make the following tests: 

36 



FRUITS AND FRUIT PRODUCTS 37 

Salicylic Acid 

Place a few drops of this extract in a test tube and add a 
drop or two of a 0.5 per cent solution of ferric chlorid. If 
salicylic acid is present, there will be a purple coloration. 

Benzoic Acid 

Mohler's Test. — Add 2 to 3 cc. of strong sulfuric acid to 
a second portion of the above ether extract and heat until 
white fumes appear. Then add a few crystals of potas- 
sium nitrate and heat again. Continue adding the nitrate 
and heating till the solution is colorless or only a very light 
yellow. Dilute with about 5 cc. of water when cool, 
neutralize with ammonia. It should be filtered when not 
clear or when crystals of ammonium or potassium sulfate 
are formed. Add a few drops of ammonium sulfid to the 
nitrate in such a way as to prevent the mixing of the liquids. 
The sulfid will be on top. If a bright cherry-red color 
forms where the two liquids meet, either benzoic acid or 
saccharin is present. Distil and the benzoic acid will pass 
over, extract the distillate in the usual way and apply the 
above test to it for benzoic acid. 

Saccharin 

Taste a third portion of the ether extract. A very sweet 
taste indicates saccharin. A further test can be made by 
adding 1 or 2 grams of sodium hydroxid to the rest of the 
ether extract and heating a half hour in an oil bath at 
250 C. Dissolve in water when cool, acidify with dilute 
sulfuric acid and extract with ether. The saccharin will have 
been converted into salicylic acid, which may be identified 
by the usual test for that acid. This test presupposes the 
absence of salicylic acid in the original material. 



38 PURE FOOD TESTS 

COLORING MATTER 
Coal-Tar Dyes 

To attempt to identify the particular dye used in every 
case would be quite beyond the object of this set of simple 
tests. A general test showing the presence of a coal-tar 
dye is probably all that is usually desired. 

Sostegni and Carpentieri Test. — Such a test may be 
made by dissolving 15 grams of the fruit product in 100 cc. 
of water, filtering and acidifying with a small quantity of a 
10 per cent solution of hydrochloric acid and again filtering. 
Place in the filtrate strips of white woolen cloth (nun's 
veiling will do) which have been freed from grease by boil- 
ing first in very dilute caustic soda solution, then in water, 
and boil for 5 to 10 minutes. Remove the cloth and wash 
it in water, then boil in very dilute hydrochloric acid. Stir 
the cloth in water to remove the acid and dissolve the color 
by boiling in a solution of ammonium hydroxid (1 to 50). 
The time required will depend upon the particular dye 
used. Remove the cloth from the solution and acidify the 
latter with hydrochloric acid, a slight excess is better, and 
another piece of the cleansed cloth is immersed and again 
boiled. Nothing but coal-tar dyes will color in this second 
dyeing. 

Cochineal 

Girard and Dupre Test. — See tests for cochineal under 
"Catsups and tomatoes." 

Acid Magenta 

Girard and Dupre. — Make about 100 cc. solution of the 
fruit, filter, and neutralize with potassium hydroxid (strength 
5 to 100); about 2 cc. will be needed. Add 4 cc. of mercuric 



FRUITS AND FRUIT PRODUCTS 39 

acetate solution (1 to 10), shake and filter. By this treat- 
ment the filtrate should be colorless and slightly alkaline. 
Add sulfuric acid till there is a slight excess. A colorless 
solution indicates the absence of acid magenta, while a 
light violet-red shows its presence, providing the amyl- 
alcohol extract showed no other dye to be present. 

Caramel 

Amfhofs Test. — 10 cc. of a solution of the fruit is put 
into a deep, narrow glass (a bottle may be used). Add 30 
to 50 cc. of paraldehyde, to be gaged by the intensity of 
the coloring. Then add a sufficient quantity of absolute 
alcohol to make the solutions mix. If caramel is present, 
a brownish-yellow to dark-brown precipitate will be formed, 
decant, wash the precipitate once with absolute alcohol, 
dissolve in a little hot water and filter. The shade of color 
is proportional to the amount of caramel present. 

To verify the test, pour the colored fluid into a freshly 
prepared solution of phenylhydrazin (2 parts phenyl- 
hydrazin-hydrochlorid, 3 parts sodium acetate, and 20 parts 
water). Much caramel produces a dark-brown precipi- 
tate in the cold, and is hastened by slightly heating. A 
very small amount of caramel will require several hours to 
precipitate. 

APPLE-JUICE IN JELLIES MADE OF SMALL 
FRUITS 

Very often cider is added to other fruit juices to give them 
the proper consistency in jellies, jams, and marmalades. 

Its presence may some times be determined by making the 
usual starch test. A large quantity of starch is normally 



40 PURE FOOD TESTS 

present in apples, but is less as they ripen, and finally dis- 
appears in the ripened fruit. There is no starch, or only a 
mere trace, in small fruits even when green. It is readily 
seen that if the juice is taken from green apples that there 
will be starch found in the artificial jelly or jam, though its 
absence does not prove the absence of cider. 
Make the starch test as follows: 

STARCH 
In Jellies, Jams, and Such Products 

Make a solution of the jelly or jam and destroy the color 
by heating nearly to the boiling point and adding dilute 
(1:3) sulfuric acid and potassium permanganate until 
the color is destroyed. This treatment does not affect the 
starch, and when cool add iodin, preferably potassium 
iodid-iodin (potassium iodid, 0.4 gram; iodin, 0.1 gram; 
water, 20 cc). If a great quantity of starch is present an 
almost black precipitate will be formed. Smaller amounts 
give the usual blue color. 

Whenever starch is found to be present, it is best to make 
a microscopical examination in the case of jams and 
marmalades. If the starch is normally present the grains 
will be seen within the cell walls after the iodin treatment. 

Starch is nearly always present in the apple and some 
other fruits, so unless it is present in jelly and such products 
in considerable quantity it is not likely that it was added. 

GELATIN 
In Jellies 
Henzold Test. — Add water to some of the jelly and boil 
for a short time, filter and treat the filtrate with an excess 



FRUITS AND FRUIT PRODUCTS 41 

of a 10 per cent solution of potassium bichromate and boil 
again. After cooling add 2 or 3 drops of concentrated 
sulfuric acid. A white flocculent precipitate forms if 
gelatin is present, and it gradually collects in a lump at the 
bottom. 

E. Beckmann's Method. — Treat the jelly with 95 per 
cent alcohol and wash the precipitate with alcohol to free 
it from the sugar, then drive off the alcohol by heating. 
Add a very little water to the residue and neutralize the 
extract with calcium carbonate. Then add formalin and 
evaporate to dryness. By this treatment gelatin is ren- 
dered insoluble. 

Pure fruit jellies have only 1 to 2 per cent of insoluble 
precipitate, while those jellies in which gelatin is used have 
70 to 86 per cent of insoluble precipitate. 

AGAR AGAR 

Boil the sample with 5 per cent sulfuric acid. Add a 
crystal or two of potassium permanganate, and wait till it 
settles, and examine the sediment for diatoms with a micro- 
scope. Their presence shows the use of agar. 

HEAVY METALS 

Tin, Zinc, Lead, and Copper 

A. H. Allen's Method. — (See test for heavy metals 
under canned meat.) 

ARSENIC 

Marsh's Test. — Fit a 100 cc. flask with a two-holed 
rubber stopper, through which passes a long-stemmed 
separatory funnel reaching nearly to the bottom, and a 



42 



PURE FOOD TESTS 



delivery tube which connects with a bulb tube containing 
a little acetate of lead solution. This in turn is connected 
with a calcium chlorid tube and this with a small, hard 
glass tube, 15 or 20 cm. long, not over 0.5 cm. bore, and 
drawn to small size in the middle. The large part next the 
chlorid tube is protected by fine wire gauze which extends 
to within a half inch of the constricted part. Two burners 
may be so placed as to heat the gauze. The flask should 
be placed in water and the bulb tube may be. Four grams 
of arsenic-free zinc, and 40 cc. of dilute pure sulfuric acid 




Apparatus for Marsh Test 



(1 to 8) are placed in the flask. Let the hydrogen flow at 
least a quarter of an hour, then heat the gauze for 15 or 20 
minutes. There should be no deposit in the tube. Now, 
char a portion of the sample, dissolve in water and pour 
into the separatory funnel, letting it run slowly into the 
flask. A dark deposit in the glass tube shows that arsenic 
is present, but if after an hour no darkening takes place it is 
quite safe to say that no arsenic is present in the fruit. 

Gutzeifs Test. — Place a gram of pure zinc, 5 cc. of 
dilute sulfuric acid (6 per cent) and about 1 cc. of a solution 



FRUITS AND FRUIT PRODUCTS 43 

of the sample in a deep test tube. Cover the tube with 
three thicknesses of filter paper, fitted tightly over the 
mouth of the tube. Place on the upper paper a drop of 
strong silver nitrate solution. Place the tube in a dark 
place and leave for 10 minutes. If a bright yellow stain 
forms on the filter paper, and turns black or brown when 
water is added to it, arsenic is present. Unless one is 
certain of the purity of the reagents used it is advisable to 
make a blank test, using distilled water instead of the fruit. 

Oxidize all sulfids to sulfates before applying the above 
test. To find out whether they are present or not, sub- 
stitute lead acetate for the silver nitrate on the filter paper. 
To avoid some of these difficulties treat according to the 
following method: 

Preparation of the sample according to Leach. — If pos- 
sible reduce the sample to a dry char by treatment with 
concentrated nitric and sulfuric acids so that it may be 
powdered in a mortar. Dissolve out the arsenic by re- 
peated treatment with boiling water. Save this extract, 
and, when cool, filter and submit to Marsh's test which is 
given above. 

In case the sample is too much of a solid to get the arsenic 
out by the above treatment, it may be prepared according 
to the directions of Chittenden and Donaldson: Heat ioo 
grams of the macerated sample with 23 cc. of pure, strong 
nitric acid to a temperature of 150 C. or 160 C. Assist 
the action by stirring occasionally. When the fruit becomes 
a deep yellow or orange color, remove the heat and add 
3 cc. of pure, strong sulfuric acid. It should be stirred 
while nitrous fumes are passing off. Heat again to about 
180 C, and before it cools add, drop by drop, 8 cc. of pure 
concentrated nitric acid. It should be stirred constantly 



44 PURE FOOD TESTS 

while the acid is being added. Heat at 200 C. till sulfuric 
acid fumes begin to come off and only a dry mass remains. 
Powder the mass and exhaust it with boiling water, filter 
and test the solution when cold with Marsh's test. 



CHAPTER VII 

FLAVORING EXTRACTS 

LEMON EXTRACT 

The important ingredients of lemon extract are lemon oil 
and citral, its aromatic constituent. Oil of citronella and 
oil of lemon grass are sometimes substituted for lemon oil. 
Methyl alcohol is sometimes used in place of the more 
expensive spirit alcohol as a solvent for the lemon oil. 

Lemon Oil 

The presence of lemon oil may be detected by adding a 
large excess of water to a small amount of the extract in a 
test tube. If the mixture does not show some cloudiness, 
it is a strong indication that no lemon oil is present. The 
degree of cloudiness gives an idea of the amount of oil 
present. 

Citral 

This is present in the oil of lemon grass, which is some- 
times used as a substitute for lemon oil. Citral may be 
detected by the following test by Burgess: 

Add 20 cc. of sulfuric acid to 85 cc. of water. Dissolve 
in this mixture 10 grams of mercuric sulfate. Shake 2 cc. 
of the sample with 5 cc. of this reagent in a test tube. If 
citral is present, the liquid will be bright red, and will 

45 



4 6 PURE FOOD TESTS 

quickly disappear and give place to a whitish compound, 
which floats on top. 

Oil of Citronella 

This is often substituted for lemon oil. It may be de- 
tected by the same test which was used for citral. Instead 
of the red color and the white compound, citronella gives a 
bright yellow color, which does not disappear for some time. 

Tartaric or Citric Acid 

Precipitate the oil by the addition of an equal volume of 
water. Filter and add a very little of the filtrate to a test 
tube nearly full of cold lime water. A precipitate will 
form if tartaric acid is present and it will dissolve in an 
excess of ammonium chlorid or acetic acid. Filter, or, in 
case no precipitate forms, heat the liquid. Citric acid is 
precipitated in the presence of a large excess of hot lime 
water. 

Methyl Alcohol 

Mullikin and Scudder. — Take 2 ft. of No. 12-15 copper 
wire and bend at right angles about 8 or 10 inches from one 
end. Grasp this bent end and an ordinary lead pencil 
side by side in such a way that the bend will be about the 
middle of the pencil. Wind the wire around the pencil 
and toward the free end of the short part of the wire until 
you have a coil 3 or 4 cm. long. Remove the pencil and 
twist the unwound parts together for a handle for the coil. 

Dilute a portion of the sample 3 or 4 times, and oxidize 
10 cc. of the diluted liquid (preferably in a test tube) by 
heating to a red heat the above copper coil in the oxidizing 
flame of a Bunsen lamp. Thrust the heated coil quickly 
into the liquid contained in the test tube. In a second 



FLAVORING EXTRACTS 47 

withdraw and immerse in water. Continue this operation 
till the oxid of copper fails to be reduced (usually 4 or 5 
times is sufficient). Cool the liquid by immersing the tube 
in water. Separate into two parts and test each for formal- 
dehyde by the following methods: 

Mullikin, S. P. — Place one of these parts in an evap- 
orating dish, and add to it 1 cc. of strong ammonia, boil 
gently over the free flame till the vapors cease to smell of 
ammonia. Add 2 or 3 drops of strong hydrochloric acid 
and heat just to boiling, and cool quickly by dipping the 
dish in cold water. Make the test for formaldehyde: Add 
a drop of a solution of resorcin (1 : 200) and pour this mix- 
ture slowly down the side of an inclined test tube which 
contains 3 cc. of strong sulfuric acid, taking care to keep 
the liquids separate. After 3 minutes give the tube a rotary 
motion by rolling between the hands for a minute or more 
but only gradually mixing the water and acid, but mixing 
only about half of the acid. 

Flecks of a rose-red color form if methyl alcohol is present. 
Bands of color or flecks of other colors, even though they 
be tinged with red or a rose-red solution without the pre- 
cipitate, should never be taken as proof that methyl alcohol 
is present. These conditions, however, are good grounds 
for repeating the test; 10 per cent or even less may be de- 
tected by this test. 

Hydrochloric Acid and Ferric Chlorid Test. — Add a few 
drops of the other part of the above oxidized liquid to about 
10 cc. of milk, known to be free from formaldehyde, in a 
porcelain casserole, and add 10 cc. of commercial hydro- 
chloric acid (sp. gr. 1.2) which contains 1 cc. of 10 per cent 
ferric chlorid per 500 cc. Heat slowly over the open flame 
nearly to boiling. Give the liquid a rotary motion to break 



48 PURE FOOD TESTS 

up the curd. If formaldehyde is present, the liquid will 
be colored violet. If not, it slowly turns brown. The 
presence of formaldehyde proves that methyl alcohol was 
in the original extract. 

Coloring Matter 

Preliminary Test. — Treat the sample with strong hydro- 
chloric acid, and if tropaeolin or methyl orange be present the 
solution will turn pink; Martius yellow partially decolor- 
izes the solution; dinitrocresols decolorizes the solution. 
Turmeric or naphthol yellow produces no color change. 

Turmeric 

Turmeric may be detected by soaking a piece of filter 
paper in the sample, drying and dipping it in a dilute solu- 
tion of boric acid or borax which has been slightly acidu- 
lated with hydrochlorid acid. Dry again and a cherry-red 
color forms if turmeric is present. Add a drop of dilute 
alkali and if turmeric be present the paper will be colored 
dark olive. 

Coal-Tar Colors 

Evaporate some of the extract to dryness; take up the 
residue with water and extract the coal-tar colors if present, 
and test for them by the method given under canned vege- 
tables. 

VANILLA EXTRACTS 

The best grades of vanilla extract are made by treating 
vanilla beans with 50 per cent alcohol. Coumarin, an 
extract from tonka beans, may be used in making the ex- 
tract. This of course would make a cheaper product. If 
less than 50 per cent alcohol is used in making the extract, 
some alkali must be added to dissolve the resins which will 



FLAVORING EXTRACTS 49 

not dissolve in a weaker alcohol. In artificial extracts some 
such coloring matter as caramel or tannin is used. 

Preliminary Test. — To a portion of the extract add a 
few drops of lead acetate solution. The absence of a bulky 
flocculent precipitate shows the extract not to be of high 
quality. Leach recommends that normal acetate of lead 
be added to the sample, and if a precipitate does not form 
it is conclusive evidence that it is not a pure extract. 

When a precipitate forms with the above reagent, it 
should settle immediately and leave a clear and almost 
colorless liquid. When there is a mere cloudiness only, it 
may be due to caramel, in which case the extract is to be 
suspected. 

Alkali 

Shake a portion of the sample with twice its volume of 
water. If no precipitate forms, an alkali is present. A 
flocculent reddish-brown precipitate shows no alkali is 
present. If the solution is milky it indicates the presence 
of a foreign resin. 

Add hydrochloric acid drop by drop to the diluted extract. 
Nothing more than a mere turbidity should result. Should 
it be quite turbid and the color fading after a time, it shows 
that an alkali has been used. 

Foreign Resins 

Mix a portion of the extract slowly with twice its volume 
of water, frequently shaking the mixture. When this 
solution is milky, it indicates a foreign resin. 

Hess* Test. — Dealcoholize 25 cc. of the sample by con- 
centrating on the water-bath, adding water from time to 
time to retain the original volume. When no alkali is 
present in the extract, pure vanilla resin will be thrown 



So PURE FOOD TESTS 

down as a reddish-brown flocculent precipitate. Collect 
the resin, whatever its color, on a filter, and wash. Save 
the nitrate to test for caramel. Place a piece of the paper 
and resin in a dilute solution of potassium hydroxid. If the 
resin is that of pure vanilla it will dissolve, giving a deep- 
red color, and is reprecipitated when the alkali is neutralized 
with hydrochloric acid. Dissolve another part of the 
precipitate in alcohol, and to a part of this solution add 
a few drops of ferric chlorid; and to the other part, hydro- 
chloric acid. There should be no marked coloration in 
either case if the resin is that of pure vanilla. Foreign 
resins nearly always produce a coloration. 

Caramel 

Shake the bottle of vanilla, and if the bubbles, which 
form, are a bright caramel color, keeping the color till all 
are gone, the presence of caramel is indicated. 

Concentrate a portion of the filtrate, which was saved in 
making the test for foreign resins, at a rather low temper- 
ature until it has about the same color as the original extract. 
Add a few drops of strong hydrochloric acid and heat very 
gently. If caramel is present, a yellowish-red flocculent 
precipitate will form. After the liquid cools, filter and 
wash with water. Should this precipitate contain caramel, 
it will not dissolve in water, ether, and alcohol, but will 
dissolve in sodium hydroxid, dilute alcohol, and glacial 
acetic acid. 

Tannin 

Test another portion of the filtrate made in testing for 
foreign resins, with a few drops of a solution of gelatin. A 
slight precipitate only should form due to the presence of a 



FLAVORING EXTRACTS 51 

small amount of tannin normally present in this filtrate. 
A large excess shows that it has been added to the extract. 

Coumarin 

Leach's Test. • — Dealcoholize a portion of the sample as 
above and treat with ammonia, add 3 or 4 volumes of 
chloroform in a separatory funnel. Evaporate the chloro- 
form extract in an oven, not permitting the temperature to 
rise above 6o° C. To the residue add a few drops of water; 
warm gently, and add a little of a solution of 1 gram of crys- 
tallized potassium iodid in 50 cc. of water, and the solution 
saturated with iodin. If coumarin is present, a brown, 
precipitate will form, and if stirred with a rod it will collect 
in dark green flecks. 



CHAPTER VIII 

SACCHARINE PRODUCTS 

HONEY 

Bees are sometimes fed with cane sugar. Often glucose 
syrup is poured over honeycomb from which the honey has 
been extracted, and the mixture sold as genuine honey. 

Gelatin may be added to increase the weight or to thicken 
the more voluble adulterants. 

The ash of genuine honey is not over 0.3 per cent. When- 
ever the ash is greater than this it should be tested for 
calcium sulfate, the presence of a considerable quantity of 
which is an almost certain proof that starch glucose or 
invert suger has been added to the honey. Sulfates may 
be detected by adding barium chlorid to the aqueous solu- 
tion of the honey and precipitating barium sulfate. 

If the ash is high and considerable chlorids are present, 
molasses has quite probably been added to the honey. The 
presence of chlorids may be determined by the addition of 
silver nitrate which precipitates silver chlorid. 

CANE SUGAR 

The presence of cane sugar can be detected with certainty 
only by the use of the polarimeter. Its presence in large 
quantity gives a high right-handed rotation. 

52 



SACCHARINE PRODUCTS 53 

COMMERCIAL GLUCOSE SYRUP 

Allen's Test. — Make the test for dextrine which is 
present in commercial glucose, but not in pure honey. 
Dilute a portion of the honey with an equal volume of water 
and add methyl alcohol with constant stirring until there is 
a permanent turbidity. If glucose syrup is present a heavy 
gummy precipitate will soon form. Genuine honey gives 
only a slight milkiness. 

GELATIN 

Dilute a portion of the sample and add a solution of 
tannic acid. A precipitate indicates the presence of gelatin. 

Treat the sample with alcohol, and gelatin, if present, 
will be left undissolved, and it will give its characteristic 
odor on ignition. 

MAPLE SYRUP 

This is sometimes adulterated with glucose, molasses, 
golden syrup, and with ordinary white sugar. There are no 
satisfactory simple chemical tests for these substances. 

Pure maple syrup should have an ash not lower than 
0.35 to 0.40 per cent. A lower ash shows that cane sugar 
has been added. A higher ash would indicate the presence 
of molasses or brown sugar stock. These last two adul- 
terants, if present in great abundance, may be detected by 
taste. 

Glucose 

This may be detected by the use of the polarimeter. Pure 
maple syrup gives 53.1 to 60 direct, and — 22.2 to — 21.9 
after hydrolysis. Maple syrup adulterated with glucose 
gives 80 to 100 direct and 18.9 to 45.6 after hydrolysis 
(according to Ogdon). 



CHAPTER IX 

SPICES 

MUSTARD 

Mustard is often adulterated with mustard hulls, wheat, 
and rice. And when white-colored flour of any kind is 
used, turmeric, Martius yellow, or a coal-tar color is em- 
ployed to give the mixture the color of mustard. Cayenne 
pepper is occasionally used to impart pungency to diluted 
mustard. 

FLOUR 

Boil 2 grams of the mustard in 4 or 5 cc. of distilled water 
for about 10 minutes. After it is cool, add a few drops of 
iodin solution slowly, avoiding a large excess though having 
a little uncombined iodin. If a blue color is produced, 
some starchy matter has been added to the mustard. The 
intensity of the reaction is an indication of the amount of 
starchy matter used. Pure mustard contains no starch 
and hence gives no reaction with iodin. 

COLORING MATTER 

Pure mustard is a very light dull yellow, and whenever 
the sample is bright yellow, there is good grounds for sus- 
pecting the presence of some artificial coloring matter. 

54 



SPICES 55 

Turmeric 

Add strong ammonium hydroxid to the mustard, and if 
turmeric is present an orange-red color is usually produced. 

Make an alcoholic extract of the sample and dip a piece 
of filter paper in it, and when dry draw it through a cold, 
saturated solution of boric acid in water. An orange or 
red-brown tint produced on the paper indicates the pres- 
ence of turmeric. 

Thoroughly mix 2 or 3 grams of the mustard with castor 
oil and filter. If turmeric is present the filtrate will appear 
fluorescent. 

Extract a portion of the sample with 3 times its weight 
of wood alcohol and filter. Evaporate one half of the solu- 
tion to dryness and add a little hydrochloric acid to the 
residue. This will turn red whenever turmeric is present, 
and if an excess of alkali be added it will change to a greenish 
blue. Evaporate the other half to dryness and moisten 
with a solution of boric acid and dry on a steam bath. A 
cherry-red color indicates turmeric. 

Martius Yellow or Analogous Coal-Tar Coloring 

Matter 

Extract the slightly acidified sample with 95 per cent 
alcohol and dye wool as directed under " Vegetables. " 
The wool will be dyed a bright yellow. 

Allen's Test. — Treat a portion of the sample with cold 
alcohol, and shake vigorously for 5 minutes, then filter and 
evaporate the filtrate to dryness; add enough water to take 
up the residue and dye some white wool in this liquid as in 
the last test. When the dyed wool is wrapped in white 
paper and heated to 120 in an air bath, part of the coloring 



56 PURE FOOD TESTS 

matter will be transferred to the paper. The coloring 
matter dissolves readily in dilute ammonia or hot water, 
and on the addition of hydrochloric acid the solution is 
decolorized and a yellow precipitate formed. This distin- 
guishes it from picric acid. 

Cayenne Pepper 

Allen's Test. — Boil i gram of the mustard for a few 
minutes with alcohol, filter, and evaporate to dryness at 
about ioo°. Taste the residue and cayenne may be recog- 
nized by its pungency. Or heat a portion of the extract, 
and smell the fumes. Irritation of the lungs and coughing 
will surely follow if cayenne pepper is present. 

PEPPER 

Pepper may be adulterated with wheat, buckwheat, 
pepper husks, ground olive stones, spent ginger. Cayenne 
pepper is sometimes added to adulterated pepper to give it 
the normal pungency. Many of these adulterants can be 
detected only by the aid of the microscope. 

Neuss's Test. — True pepper turns an intense yellow 
when covered with strong hydrochloric acid. Any adul- 
teration can be detected at once by the color. 

Ground Olive Stones or "Poivrette" 

Make a paste of the pepper with caustic alkali. Dilute 
with a large quantity of water and wash by decantation. 
Olive stones will be colored a bright yellow; pepper-husks 
will appear dark. 

Jumeau's Test. — Dissolve 5 grams of iodin in a mixture 
of 50 cc. of ether and 50 cc. of alcohol. Cover the bottom 
of a porcelain capsule with the finely ground pepper, and 



SPICES 57 

add just enough of the iodin mixture to wet the entire mass, 
and mix well till it has the same consistency throughout. 
Let dry in the air, then powder and examine it, and if olive 
stones are present they will be colored yellow. Pure 
pepper would have a deep brown color. 

Aniline acetate, one part aniline in 3 parts acetic acid, 
colors pure pepper gray or white and olive stones yellowish 
brown. 

Cayenne 

Heat some of the red particles found in the pepper and 
their characteristic vapor is produced. Dissolve the par- 
ticles in alcohol or ether and the same vapors are produced. 



CHAPTER X 

VINEGAR 

Vinegars may be adulterated by the addition of mineral 
acids as sulfuric or hydrochloric. Caramel or the coal-tar 
dyes may be employed to improve the color or to give color 
to an artificial product. Malic acid is always present in 
cider vinegar. Potassium acid tartrate occurs in true wine 
vinegar. Poisonous metals may be present in vinegars 
containing free mineral acid. Entirely artificial cider 
vinegar is often found on the market. 

Preparation of the Sample for Testing 

If the vinegar is turbid from any suspended matter, it 
should be filtered. The samples should be analyzed at 
once, and in the laboratory they should always be kept in 
glass-stoppered bottles. 

General Observations. — Ignite a little of the vinegar 
residue on a clean platinum wire in a colorless Bunsen 
flame, and if it is pure cider vinegar the flame will be 
colored the characteristic lilac color of potassium. The 
sodium flame is absent or only a mere trace of it is present. 
But in all artificially colored vinegars, spirit sugar and 
glucose vinegars, the sodium flame predominates. 

The residue of cider vinegar is thick, viscid, or mucilag- 
inous, of a light brown color, astringent acid taste though 
not unpleasant. The solids of sugar-house vinegar, those 

58 



VINEGAR 59 

from colored spirit and wood vinegar, each have a bitter 
taste on account of the caramel used to color them. The 
residue of the sugar-house vinegar has the odor of molasses. 
Wood vinegar when present gives a residue with a tarry or 
smoky taste and smell. Glucose vinegar gives the odor 
of scorched corn. Solids of fruit vinegars are quite soluble 
in alcohol, except a granular residue in grape vinegar, 
while the solids of malt and glucose vinegars are almost 
insoluble. 

The ash of fruit vinegars and malt vinegars has a 
distinct alkaline reaction, while that of spirit and wood 
vinegars is very feebly alkaline. 

CIDER VINEGAR 

To 10 cc. of the vinegar add a few drops of neutral lead 
acetate solution. If the sample is cider vinegar a pre- 
cipitate will form. 

FREE MINERAL ACIDS 

The ash of pure cider vinegar is always alkaline. If a 
vinegar should show a neutral reaction this would cer- 
tainly indicate the presence of a free mineral acid. If the 
ash be alkaline, no acid except nitric could have been 
present, and this is seldom, if ever, used as an adulterant 
of vinegar. 

Methyl Violet Test. — Dilute 5 cc. of the vinegar with an 
equal amount of water, and mix thoroughly. Add 4 or 
5 drops of methyl violet solution made by putting one 
part of methyl violet 2 B. in 10,000 parts of water. A 
blue or green color indicates the presence of free mineral 
acids. 



60 PURE FOOD TESTS 

When the Ash is Alkaline Apply 

Ashby's Test. — Extract 0.5 gram of logwood in 100 
cc. of water and dry a drop or two on a porcelain surface. 
Then add a drop of the vinegar and dry again. If the 
residue is red, a mineral acid is present; if yellow, mineral 
acids are absent. When only a very small amount of the 
acid is present the red coloration will be destroyed on 
diluting with water, but may be restored by concentrating 
the liquid. 

Sulfuric Acid 

Sulfuric acid, if present, will cause the vinegar to leave 
a charred mass when evaporated over the water-bath. 

Frear's Method. — Mix 5 cc. of the sample and 5 or 
10 cc. of water, and add a very little of a solution of 
methyl violet (made by dissolving one part of methyl 
violet 2 B. in 100,000 parts of water). A blue or green 
coloration shows the presence of mineral acids. 

Sulfuric Acid as Distinguished from Sulphates 

Allen's Method. — Evaporate 100 cc. of the vinegar 
down to one tenth its volume, and when cold add 50 cc. 
of alcohol. Sulfuric acid remains in solution while the 
sulfates are precipitated. Dilute the solution and pre- 
cipitate the acid with barium chlorid. 

HYDROCHLORIC ACID 

Free 

Place a definite quantity of the vinegar in a distilling 
flask and distil off half. Add a few drops of silver nitrate 



VINEGAR 61 

to the distillate. If a precipitate forms, hydrochloric 
acid is present. 

MALIC ACID 

Leach' 's Method. — To 5 cc. of the sample, add a few 
drops of a solution of calcium chlorid (1 : 10) ; make slightly 
alkaline with ammonia. Filter off any precipitate that 
may form, add 20 to 30 cc. of 95 per cent alcohol to the 
nitrate and heat to boiling. If malic acid is present, a 
voluminous rlocculent precipitate will form. A precipitate 
may form in vinegars containing dextrin. Make a further 
test for malic acid by the following: Filter and treat the 
precipitate with a little alcohol, and when dry add con- 
centrated nitric acid and evaporate to dryness on a water- 
bath. Treat the residue with sodium carbonate, boil for a 
short time, filter. Add acetic acid to the filtrate till 
slightly alkaline, boil till carbon dioxid is expelled, and if 
on the addition of calcium sulfate a precipitate forms, 
it indicates the presence of mafic acid. 

COLORING MATTER 

Caramel 

The residue of vinegar to which much caramel has been 
added has an unusually dark color and bitter taste. 

Crampton and Simons' Method. — Shake well together 
in a corked flask 50 cc. of the vinegar with about half as 
many grams of fuller's earth; after standing for half an 
hour filter. Vinegar containing no artificial color will 
show scarcely any change in color when thus treated. A 
caramel-colored vinegar will be decolorized in proportion 
to the amount of caramel present. 



62 PURE FOOD TESTS 

Coal-tar Colors in Wine Vinegar 

Test by the usual test for coal-tar dyes. See under 
canned vegetables. 

METALLIC IMPURITIES 

Vinegars containing free mineral acids are sometimes 
found to contain poisonous metals. 

Evaporate 200 to 400 cc. of the vinegar to dryness, add 
a little sodium hydroxid to this residue and burn to an 
ash over a low flame. It may be necessary to add a little 
potassium nitrate once or twice. Add a little dilute 
hydrochloric acid and saturate with hydrogen sulfid and 
test for lead, zinc, copper and arsenic according to Allen's 
method given under canned meats. 

Spices to Increase Pungency 

Leach. — Neutralize a portion of the vinegar with 
sodium carbonate. The presence of spices is easily de- 
tected by tasting this mixture. 

Another Test. — Exactly neutralize a little of the 
vinegar as above, evaporate to smaller bulk and taste as 
before, then shake the concentrated liquid with ether, 
separate the ethereal layer and evaporate it, and taste the 
residue. 

Tartar in Wine Vinegar 

The presence of tartar in vinegar proves it to be wine 
vinegar. 

Allen's Method. — Evaporate a portion of the vinegar 
and treat the residue with alcohol; a granular residue of 



VINEGAR 63 

tartar remains undissolved. To prove that it is tartar, 
decant the alcohol and dissolve the residue in a little hot 
water, cool, rub the inside of the vessel with a glass rod, 
and if tartar was present acid potassium tartrate will be 
deposited where the rod touched the vessel. The test 
will be more sensitive if an equal volume of alcohol is 
added. 

Free Tartaric Acid in Wine Vinegar 

Test as for Tartar. — Treat the alcoholic solution of the 
extract with an alcoholic solution of potassium acetate. 
Rub the sides of the vessel as before, and if tartaric acid 
is present the streaks and sometimes a precipitate forms 
where the rod touches the vessel. 

GLUCOSE 

Whenever glucose is present in a vinegar, a precipitate 
nearly always forms on the addition of ammonium oxalate. 



CHAPTER XI 

FATS AND OILS 

LARD 

Lard is very often adulterated with cottonseed oil, 
cottonseed stearin and beef stearin. Their being very 
much cheaper accounts for the sophistication. 

Cottonseed Oil 

Halphen's Test. — Dissolve i per cent of sulfur in a 
given volume of carbon bisulfid. Add an equal volume of 
amylic alcohol. Mix 3 to 5 cc. of this reagent with an 
equal volume of the melted lard in a test tube. Close with 
a cotton stopper and boil for 15 minutes in a bath of satu- 
rated brine. The presence of cottonseed oil is indicated 
by a deep-red or orange color, little or no color resulting in 
its absence. Lard from hogs fed on any of the various 
cottonseed products may give a faint reaction when this 
test is applied. 

Cottonseed Stearin 

Since cottonseed stearin is only the more solid portions 
of cottonseed oil, the above test may be applied, but to 
distinguish it from the latter it is necessary to make deter- 
minations quite beyond the scope of this set of tests. 

64 



FATS AND OILS 6$ 

Beef-Stearin 

It is very difficult to identify beef-stearin by chemical tests. 
It is usually detected by use of the microscope. Leach 
gives the following method: Make a solution of 2 to 5 grams 
of the fat in 10 to 20 cc. of ether. Let stand a half day, 
at about the room temperature. Loosely stopper the tube 
with cotton to prevent too rapid evaporation of the ether. 
It is well to vary the conditions of heat, amount of solvent, 
and rate of crystallization, to get the best possible results. 
It may often be well to separate the crystals thus obtained 
by filtering and recrystallizing from ether. Separate the 
crystals that form at the bottom of the test tube from the 
liquid portion by pouring on a small filter. Wash them 
several times with ether, but not sufficient to remove the 
mother liquor entirely. In case it is all removed, and the 
crystals are too fragile to mount, add a drop of alcohol. 
Crystals of lard stearin are flat rhomboidal plates, one end 
being oblique to the sides, and they do not appear to be 
regularly grouped. Beef-stearin crystals are rod-shaped, 
or needles of ten apparently curved with pointed ends, and 
are arranged in clusters like the ribs of a fan, the crystals 
radiating from a common point. Under certain conditions 
the lard crystals are not irregularly grouped, but are arranged 
like the parts of a feather, where one part seems attached 
to another close at hand. Considerable experience is neces- 
sary to use this test with absolute certainty. 

OLIVE OIL 

Olive oil is one of the most commonly adulterated foods. 
The commonest adulterant probably is cottonseed oil. 
Other foreign oils, such as peanut, sesame, and rape, are 
sometimes used. 



66 PURE FOOD TESTS 

Preliminary Test. — Pure olive oil turns from a pale to 
a dark-green color in a few minutes, when it is shaken with 
the same volume of concentrated nitric acid or sulfuric 
acid. Whenever a reddish to an orange, or brown color- 
ation results, the presence of a foreign vegetable oil is in- 
dicated (probably a seed oil). 

Bach gives the following results of strong nitric acid on 
the common oils. Olive oil when shaken with nitric acid 
gives a pale green, which changes to an orange yellow after 
heating five minutes. With similar treatment peanut oil 
gives pale rose and brownish yellow; rape oil, pale rose and 
orange yellow; sesame oil, white and brownish yellow; 
sunflower oil, dirty white and reddish yellow; cottonseed 
oil, yellowish brown and reddish brown; castor oil, pale 
rose and golden yellow. 

PonteVs Test; Elaiden Test. — Treat i cc. of mercury 
with 12 cc. of cold nitric acid (sp. gr. 1.42) and shake 2 cc. 
of this freshly-made solution with 50 cc. of the sample in 
a bottle every 10 minutes for 2 hours. Oils which are 
principally olein, or mixtures of olein and solid esters like 
palmatin and stearin, give more or less solid products, but 
olive oil is remarkable for the firmness of the canary or 
lemon-yellow mass which is formed. After standing a day 
the mass cannot be pierced with a glass rod and sometimes 
it gives forth a sound when struck. 

This test requires considerable experience to be used with 
any great degree of certainty. 

Cottonseed Oil 

Carbon bisulfid containing 1 per cent of sulfur in solu- 
tion is mixed with an equal amount of amyl alcohol. Equal 
volumes (about 3 cc. of this reagent and the sample, are 



FATS AND OILS 67 

mixed in a test tube, which is loosely stoppered with cotton, 
•and heated in a bath of boiling saturated brine for a quarter 
of an hour. The presence of cottonseed oil is shown by the 
formation of a deep-red or orange color. Little if any 
color is produced in its absence. If no color is produced 
it is well to add another cc. of the reagent and heat 5 or 10 
minutes more, and to repeat this again if no color forms. 
Lard and lard oil from animals fed on cottonseed meal 
may give a faint reaction. 

Peanut Oil (Arachis Oil) 

Bellier's Test. — Saponify a gram of the sample with 5 
cc. of a solution of 85 grams potassium hydroxid in a liter 
of strong alcohol. This may be done in a small Erlen- 
meyer flask on the water-bath. Then boil for two minutes, 
neutralize exactly with dilute acetic acid (use phenolphtha- 
lein as the indicator). Cool the mixture by placing the 
flask in water at 17 to 19 C. A precipitate usually forms. 
Add 50 cc. of 70 per cent alcohol which contains one per 
cent by volume of concentrated hydrochloric acid (sp. gr. 
1.2). Shake the flask vigorously and cool again as before. 
If no precipitate forms the oil is not adulterated with peanut 
oil. The presence of 10 per cent or more of peanut oil 
produces a precipitate, even a smaller amount will produce 
a cloudiness after standing between 17 and 19 C. for 30 
minutes. 

Some varieties of olive oil from Tunis give the same 
turbidity when the 70 per cent alcohol is added. To dis- 
tinguish these from peanut oil heat the mixture on the 
water-bath till everything has dissolved, and cool to 17 to 
1 9 . The cloudiness will not appear if the oil is pure, but 
will reappear if peanut oil is present 



68 PURE FOOD TESTS 

Sesame Oil 

Badouin's Test. — About o.i of a gram of cane sugar is 
dissolved in 10 cc. of hydrochloric acid (sp. gr. 1.20) shaken 
vigorously with 20 grams of the sample for a minute or 
more. After standing for a while the aqueous solution will 
separate from the oil. If 1 per cent or more of sesame oil 
is present, the aqueous solution will be colored crimson. 

Tocher's Test. — Dissolve 1 gram of pyrogallic acid in 
15 cc. of strong hydrochloric acid. Add an equal volume 
of the oil in a separatory funnel. When it has stood a 
minute, draw off the aqueous solution and boil. In the 
presence of sesame oil it is colored red by transmitted light, 
and blue by reflected light. 

Rape Oil 

Palas* Test. — Make a 1 per cent solution of fuchsin and 
a 30 per cent solution of sodium acid sulfite. Mix together 
20 cc. of each of these solutions and add 200 cc. of water 
and 5 cc. of strong sulfuric acid. After the solution is 
decolorized, 10 cc. of the sample is shaken with it. If rape 
oil is present, the color will be partially restored. To 
prevent the formation of the color by contact with the air 
have the vessel full of the mixture. 



CHAPTER XII 

BEVERAGES 
COFFEE 

Coffee is often colored with such substances as Scheele's 
green, chrome yellow, iron oxide, Prussian blue, indigo and 
turmeric. Imitation coffee beans have been made of wheat 
flour, bran, rye, chicory and peas. 

Allen's Preliminary Test. — A good preliminary test for 
ground coffee is to sprinkle some of it on the surface of cold 
water. The oil of true coffee prevents the particles from 
being readily soaked, and so they float for some time. 
Chicory and most of the other adulterants of coffee contain 
no oil, but do contain caramel, which is quickly extracted 
by the water producing a zone of brown color about such 
particles. They become soaked and quickly sink. The 
liquid containing pure coffee diffuses uniformly without 
coloring the water to any perceptible degree. Chicory and 
similar roots give a dark brown, turbid infusion. Roasted 
cereals do not impart so distinct a color to water. 

Coloring Matter 

Shake the coffee beans in cold water and make the regular 
qualitative tests for the inorganic coloring matters — 
Scheele's green may be identified by testing for copper and 
arsenic; chrome yellow, by testing for lead chroma te; iron 
oxide may be detected by its characteristic tests. 

69 



70 PURE FOOD TESTS 

Organic coloring matter is best extracted with alcohol. 
Prussian blue may be detected by dissolving it from the 
sediment with hot caustic alkali, acidifying with hydro- 
chloric acid, treating it with a drop of ferric chlorid. If 
present, ferric ferrocyanide, a blue precipitate, will be 
formed. Indigo is not discharged by sodium hydroxid, 
while Prussian blue is. It will form a deep blue solution 
with sulfuric acid. 

Test for turmeric as under mustard. 

Imitation Coffee Beans 
Most imitation coffee, as already stated, is heavier 
than water. Coffee contains no starch, so the imitation 
beans made of cereals may be detected by testing for 
starch. The artificial beans may also be identified by 
their uniformly regular form. Roasted cereals are glossy. 
If legumes are present pieces of hulls are usually present. 

Starch 
Allen's Method. — Boil the coffee in 10 parts of water. 
When perfectly cold add to it a little sulfuric acid, then a 
strong solution of potassium permanganate, drop by 
drop, with constant shaking, till the liquid is almost 
decolorized; strain or decant and add to the solution a 
solution of iodin. If i per cent or more of starch is 
present a blue coloration will be produced. 

Chicory 
Ritmningtori 's Test. — Boil a portion of the sample with 
water which contains a little sodium carbonate; decant, 
wash and treat the residue with a weak solution of bleach- 
ing powder for several hours. The solution will be 



BEVERAGES 71 

decolorized. The coffee will be at the bottom as a dark 
layer while the chicory will be a light layer above it. 

Albert Smith's Test. — Boil 10 grams of the sample in 
250 cc. of water; strain and add basic lead acetate in 
slight excess. A precipitate forms, and when it has 
settled the supernatant liquid will be colorless if the 
coffee is pure, but more or less colored if chicory is present. 

TEA 

Tea is adulterated by the substitution of inferior grades 
for those of better quality, by the addition of exhausted 
leaves and foreign leaves, by the use of coloring matter or 
''facing" such as Prussian blue, indigo or turmeric to 
color green tea, and sometimes graphite to color black 
tea. Foreign astringents (generally catechu) are added 
to conceal the presence of exhausted leaves. An imitation 
tea, "lie tea," is made of the stems and dust with mineral 
matter, and some starch or gum to hold these together. 

Foreign Leaves 

Though there are several chemical tests for foreign 
leaves, none are as satisfactory as a microscopical exami- 
nation. Soften the leaves by soaking in hot water, unroll 
carefully and examine with a hand lens or low power of 
the microscope. Compare with a genuine leaf — the 
shape, margin and venation. 

Exhausted Tea Leaves 

Sometimes such leaves may be detected by a physical 
examination. They are often more or less unrolled and 



72 PURE FOOD TESTS 

"facing" such as Prussian blue, indigo or turmeric to 
broken on the edges. But the only certain way of ascer- 
taining their presence is to determine the soluble ash 
which is from 2.5 to 4 per cent in pure tea and usually less 
than 0.8 per cent in exhausted tea. 

Lie Tea 

This imitation tea is easily detected by pouring hot 
water over the leaves. If they are artificial, they will 
break down into the fragments of which they were made. 

Facing 

Organic coloring matter may be detected by the same 
method used for detecting such colors in coffee. 

Catechu 

Eager 7 s Test. — Boil a little of the tea in water, and add 
to the extract an excess of lead monoxid. If the tea is 
pure the addition of a solution of silver nitrate produces 
only a slight grayish precipitate, but when catechu is 
present a yellow flocculent precipitate forms. 

A FEW OF THE BEST BOOKS ON FOOD ANALYSIS 

Allen, A. H., Commercial Organic Analysis, 1898. Pub., 

Blakiston, Phila. Price, $29.50. 
Blyth, A. W., Foods, their Composition and Analysis, 1903. 

Pub., Scribner. Price, $8.40. 
Hassall, A. H., Food, its Adulterations and the Methods for 

their Detection, 1874. Longmans, Green & Co. 
Leach, A. E., Food, Inspection and Analysis, 1905. Pub., 

John Wiley & Sons, New York. Price, $7.50. 



CHEMICALS 



73 



Lefpmann, H. and Beam, W., Select Methods of Food Analysis, 

1905. Pub., Blakiston. Price, $2.50. 
Olsen, Pure Foods Pub., Ginn & Co. Price, $.80. 
U. S. Dept. of Agr., Bureau of Chem. 
Bulletin 107, Methods of Analysis of Foods, 1908. 
Wiley, Foods and their Adulteration. 

The following are the chemicals used in making all the 
tests in this book. Most of these are found in every 
chemical laboratory. The more uncommon ones may be 
obtained from Eimer and Amend, 205-211 Third Avenue, 
New York, or from Bausch and Lomb Optical Co., Roches- 
ter, N. Y. 



Acetic acid 

Ammonium carbonate 

Ammonium chlorid 

Ammonium hydroxid 

Ammonium molybdate 

Ammonium oxalate 

Ammonium sulfid 

Amyl alcohol 

Aniline 

Barium chlorid 

Barium peroxid 

Boric acid 

Bromine 

Calcium carbonate 

Calcium chlorid 

Calcium sulfate 

Cane sugar 

Carbon bisulfid 

Castor oil 

Chloroform 

Diphenylamine 

Ether 

Ethyl alcohol 



Ferric chlorid 

Formalin 

Fuchsin 

Gelatin 

Glycerol 

Hydrochloric acid 

Iodin, tincture of 

Lead acetate (basic) 

Lead oxide 

Lime water 

Litmus paper 

Logwood chips 

Mercury, metallic 

Mercury sulfate 

Methyl alcohol 

Molybdic oxid 

Nitric acid (sp. gr. 1.42) 

Oxalic acid 

Petroleum spirit 

Phenolphthalein 

Phenylhydrazine hydrochlorid 

Phosphoric acid 

Potassium bichromate 



74 PURE FOOD TESTS 

Potassium carbonate Sodium acetate 

Potassium chromate Sodium acid sulfite 

Potassium ferrocyanid Sodium carbonate 

Potassium hydroxid Sodium chlorid 

Potassium iodate Sodium hydroxid 

Potassium iodid Starch 

Potassium nitrate Sulfur 

Potassium permanganate Sulfuric acid 

Pyrogallic acid Tannic acid 

Rennet, standard extract Turmeric paper 

Resorcin Zinc (arsenic free) 
Silver nitrate 



INDEX OF AUTHORS AND TESTS 

PAGE 

Allen, A. H., Aniline red in ground meats 15 

Glucose in honey 53 

Heavy metals in fruits and fruit products ... 41 

in meat 13 

in vinegar 62 

Sulfuric Acid (distinguished from Sulfates) in 

vinegar 60 

Tartar in vinegar 62 

Amthor, Caramel in fruit and fruit products 39 

Ashby, Free mineral acids in vinegar 60 

Bechman, Gelatin in jellies 41 

Bell and Carter, Alum in flour 18 

Blyth, Alum in bread 21 

Boettger, Ergot in rye flour 20 

Bornstein, Saccharin in canned vegetables 30 

Courley and Coremon, Horseflesh in other meats 16 

Delarne, Age of eggs 16 

Ebers, Diseased meat 16 

Frear, Sulfuric acid in vinegar 60 

Geisler, Coal-tar colors in butter 7 

Girard and Dupre, Acid magenta in catsups and tomatoes 38 

Cochineal in catsups and tomatoes ... 32 

Cochineal in canned vegetables 34 

Gutzeit, Arsenic in canned fruits 42 

Halphen, Cottonseed oil in lard 64 

Hehner, Formaldehyde in milk 4 

Henzold, Gelatin in jellies 40 

Hess and Doolittle, Process or renovated butter test for . . 7 

Hess, Foreign resins in vanilla extract 49 

Kammerer, Sulfurous acid in meat 11 

75 



76 INDEX 

PAGE 

Kleeburg, Wheat in rye flour , 20 

Klingler and Bujard, Cochineal carmine in meat 15 

Kraemer, Corn meal in wheat flour 19 

Leach, Caramel in milk , 2 

Coumarin in vanilla extract 51 

Malic acid in vinegar 61 

Salicylic acid in milk 5 

Salicylic acid in meat 12 

Lythgoe, Coal-tar colors in milk 3 

Marsh, Arsenic in canned fruits 41 

Martin, Coloring matter in butter 6 

Mohler, Benzoic acid in meat 12 

Benzoic acid in canned and bottled vegetables 31 

Benzoic acid in fruit and fruit products 37 

Mullikin and Scudder, Methyl alcohol in lemon extract 46 

Mullikin S. P., Methyl alcohol in lemon extract 47 

Peter, Benzoic acid in canned vegetables 31 

Richards, Mrs., Alum in baking powders 24 

Rimmington, chicory in coffee 70 

Schmidt, Saccharin in canned vegetables 30 

Smith, chicory in coffee 71 

Sostegni and Carpentieri, Coal-tar dyes in canned vegeta- 
bles 32 

Coal-tar dyes in fruit and fruit products 38 

Stoke, Gelatin in milk 3 

Tocher, sesame oil in olive oil 68 

Vanderplanken, Alum in sour bread 21 

Vogel, Substituted flours 19 

Wynther-Blyth, alum in flour 18 

Wolff, Tartaric acid (free or combined) in baking powders 22 



INDEX 

PAGE 

Acid magenta in fruit and fruit products 38 

Agar agar in fruit and fruit products 41 

Alkali in vanilla extract 49 

Allen, A. H., heavy metals in fruit and fruit products 41 

in meat 13 

in vinegar 62 

sulfuric acid in vinegar 60 

tartar in vinegar . 62 

test of coffee 69 

Alum in baking powders 24 

in bread , 20 

in flour 18 

in pickles 34 

Aluminium salts in cream of tartar 26 

Ammonia in cream of tartar 26 

Ammonium salts in baking powders 24 

Amthor, caramel in fruit and fruit products 39 

Aniline red in meat 15 

Annatto in butter 6 

in milk 2 

Apple juice in jellies made from small fruits 39 

Arsenic in fruit and fruit products 49 

Ashby, free mineral acids in vinegar , 61 

Bach, test of olive oil 60 

Baking powders 22 

Adulterations of 22 

Alum 24 

Ammonium salts 24 

Gypsum 24 

77 



78 INDEX 

PAGE 

Sulfates (calcium, etc.) 24 

Tartaric acid (free) 23 

Tartaric acid (free or combined) 22 

Beechman, gelatin in jellies 41 

Beef stearin in lard . . 65 

Bell and Carter, alum in flour 18 

Benzoic acid in meat 12 

in canned vegetables 30 

in fruit and fruit products 37 

Blyth, alum in bread , 21 

Boettger, ergot in rye flour 20 

Borax in fish and oysters 15 

in meats 11 

Boric acid in fish and oysters. . 15 

in meat 11 

in milk 5 

Bornstein, saccharin in canned vegetables 30 

Bread 20 

Adulterations of 20 

Alum 20 

Copper sulfate 21 

Butter 6 

Adulterations of 6 

Coloring matter 6 

Annatto 6 

Coal-tar colors 7 

Marigold * 7 

Saffron ., 7 

Turmeric 7 

Cottonseed oil q 

Oleomargarine 8 

Process or renovated butter 7 

Cane sugar in honey 52 

Canned and bottled vegetables 27 

Adulterations of 27 

Alum in pickles 34 



INDEX 79 

PAGE 

Coal-tar colors 32 

Cochineal 32 

Coloring matter 32 

Copper salts in green pickles, beans, peas, etc 33 

Turmeric in mixed pickles S3 

Examination of can or box 34 

Heavy metals other than copper (see under meats) 13 

Preservatives 28 

Benzoic acid 30 

Formaldehyde 8 

Saccharin 29 

Salicylic acid 29 

Sulf urous acid 29 

Soaked vegetables, peas, beans, and corn 33 

Caramel in fruit and fruit products 39 

in milk 2 

in vanilla extract 50 

in vinegar 61 

Catechu in tea 72 

Cayenne pepper in black pepper 57 

in mustard 56 

Cereal products 18 

Chicory in coffee 70 

Citral in lemon extract 45 

Citric acid in lemon extract 46 

Coal-tar colors in butter 7 

in canned vegetables. 32 

in fruit and fruit products 38 

in lemon extract 48 

in milk 3 

in vinegar 62 

Cochineal carmine in canned vegetables 32 

in fruit and fruit products 38 

in meat 15 

Coffee 69 

Adulterations of 69 



8o INDEX 

PAGE 

Chicory 70 

Coloring matter 69 

Imitation coffee beans 70 

Starch 70 

Coloring matters: 

Acid magenta in fruit and fruit products 38 

Aniline red in meat 15 

Annatto in butter 6 

in milk 2 

Caramel in fruit and fruit products 39 

in milk 2 

in vanilla extract 50 

in vinegar 61 

Copper salts in canned vegetables 33 

Copper sulfate in bread 21 

in flour 19 

Cottonseed oil in butter 9 

in lard 64 

in olive oil 66 

stearin in lard 64 

Coumarin in vanilla extract 51 

Courley and Coremon, horseflesh in other meats 16 

Cream of tartar 25 

Adulterations of 25 

Aluminium salts 26 

Ammonia 26 

Earthy materials 26 

Tartaric acid (free or combined) 25 

Dairy products 1 

Ebers, diseased meat 16 

Eggs, test for freshness 16 

Elaiden test 66 

Exhausted tea leaves in tea 71 

Facing in tea 72 

Fats and oils 64 

Lard 64 



INDEX 81 

PAGE 

Adulterations of 64 

Beef -stearin 65 

Cottonseed oil 65 

stearin 64 

Olive oii . 65 

Adulterations of 65 

Cottonseed oil 66 

Peanut oil 67 

Rape oil 68 

Sesame oil 68 

Fish, preservative in 15 

Flavoring extracts 45 

Flour 18 

Adulterations of . 18 

Alum 18 

Copper sulfate 19 

Substituted flours ig 

Corn meal in wheat flour 19 

Ergot in rye flour 20 

Wheat flour in rye flour 20 

Flour in mustard 54 

Formaldehyde in canned vegetables . . . 28 

in milk . 4 

Frear, sulfuric acid in vinegar 60 

Fruit and fruit products 36 

Adulterations of 36 

Agar agar 41 

Apple juice in jellies made from small fruits 39 

Arsenic. 41 

Coloring matter 38 

Acid magenta 38 

Caramel 39 

Coal-tar dyes 38 

Cochineal 38 

Gelatin in jellies 40 

Heavy metals 41 



82 INDEX 

PAGE 

Preservatives 36 

Benzoic acid 37 

Saccharin 37 

Salicylic acid 37 

Starch in jellies, jams, and such products 40 

Gelatin in honey 53 

in jellies 40 

in milk 3 

Geisler, coal-tar colors in butter „ 7 

Ginger cake, stannous chlorid in 18 

Girard and Dupre, acid magenta in fruit and fruit pro- 
ducts 38 

cochineal in catsups and tomatoes 32 

in canned vegetables 32 

Glucose in honey 53 

in maple syrup 53 

Gutzeit, arsenic, in canned fruits 42 

Gypsum in baking powders 24 

Heavy metals in canned vegetables 13 

in fruit and fruit products 41 

in meat 13 

Hehner, formaldehyde in milk 4 

Henzold, gelatin in jellies 40 

Hess and Doolittle, test for process butter 7 

Honey 52 

Adulterations of 52 

Cane sugar 52 

Commercial glucose 53 

Gelatin 53 

Horseflesh in sausage and mince-meat 16 

Hydrochloric acid in vinegar 60 

test for formaldehyde 4, 28 

Imitation coffee beans 70 

Kammerer, sulfurous acid in meat 11 

Kleeburg, wheat in rye flour 20 

Klingler and Bujard, cochineal-carmine in meat 15 



INDEX 83 

PAGE 

Kraemer, corn meal in wheat flour : 19 

Lard 64 

Adulterations of 64 

Beef -stearin 65 

Cottonseed oil 64 

stearin 64 

Leach, caramel in milk . . . s 2 

malic acid in vinegar 61 

salicylic acid in meat 12 

in milk 5 

Lemon extract 45 

Adulterations of 45 

Citral 45 

Coloring matter 48 

Coal-tar dyes 48 

Turmeric 48 

Lemon oil 45 

Methyl alcohol 46 

Oil of citronella 46 

Tartaric or citric acid 46 

Lemon oil in lemon extract 45 

Lie tea in tea 72 

Lythgoe, coal-tar colors in milk 3 

Malic acid in vinegar 61 

Maple syrup 53 

Adulterations of 53 

Glucose 53 

Marigold in butter 7 

Marsh, arsenic in fruit products 41 

Martin, coloring matter in butter 6 

Martius yellow in mustard 55 

Meats 10 

Adulterations of 10 

Canned 13 

Coloring matter (see under sausages, etc.) 15 

Heavy metals 13 



84 INDEX 

PAGE 

Preservatives (same tests as under smoked and fresh 

meat) 13 

Coloring matter 15 

Aniline red and cochineal-carmine in sausage, chopped 

meat preparations, and corned meat 15 

Diseased meat 16 

Fresh and smoked 10 

Preservatives 10 

Benzoic acid 12 

Boric acid n 

Potassium nitrate 10 

Salicylic acid 12 

Sulfurous acid n 

Fish, salt, dried, and oysters 15 

Preservatives 15 

Borax (same as under fresh meat) 15 

Boric acid (same as under fresh meat) 15 

Horseflesh in sausage and mince-meat 16 

Starch in sausage, deviled meat, and similar products. . . 15 

Metallic impurities in vinegar 4 62 

Methyl alcohol in lemon extract 46 

Mineral acids in vinegar 59 

Milk 1 

Adulterations of 1 

Coloring matter 2 

Annatto 2 

Caramel 2 

Coal-tar dyes. . . i 3 

Gelatin 3 

Preservatives 4 

Boric acid 5 

Formaldehyde 4 

Salicylic acid 5 

Starch 3 

Mohier, benzoic acid in meat 12 

in fruit and fruit products 73 



INDEX 85 

PAGE 

Mustard 54 

Adulterations of 54 

Cayenne pepper 56 

Coloring matter 54 

Martius yellow or analogous coal-tar dyes 55 

Turmeric 55 

Flour. 54 

Oil of citronella in lemon extract 46 

Oleomargarine in butter 8 

Olive oil 65 

Adulterations of 65 

Cottonseed oil 66 

Peanut oil 67 

Rape oil 68 

Sesame oil 68 

Olive stones in pepper 56 

Oysters, preservatives in 15 

Peanut oil in olive oil. 67 

Pepper (common) 56 

Adulterations of 56 

Cayenne pepper 56 

Ground olive stones 56 

Peter, benzoic acid in canned vegetables 31 

Pontet, general test of olive oil 66 

Potassium nitrate in meat 10 

Preservatives: 

Benzoic acid in canned vegetables 30 

in fruit and fruit products 37 

in meat 12 

Boric acid in fish and oysters 15 

in meat 11 

in milk 5 

Formaldehyde in canned vegetables 28 

in milk 4 

Potassium nitrate in meat 10 

Saccharin in canned vegetables 20 

in fruit and fruit products 37 



86 INDEX 

PAGE 

Salicylic acid in canned vegetables 29 

in fruit and fruit products 37 

in meat 12 

in milk 5 

Sulfites in canned vegetables 20 

Sulf urous acid in canned vegetables 29 

Process or renovated butter 7 

Rape oil in olive oil 68 

Resins, foreign, in vanilla extract 40 

Richards, Mrs., alum in baking powders 24 

Rimmington, chicory in coffee 70 

Saccharin in canned vegetables 29 

in fruit and fruit products 37 

Saffron in butter . 7 

Salicylic acid in canned vegetables 29 

in fruit and fruit products 37 

in meat 12 

in milk '. 5 

Schmidt, Albert, chicory in coffee 71 

Schmidt, saccharin in canned vegetables 30 

Soaked vegetables 33 

Sostegni and Carpentieri, coal-tar dyes in canned vegetables. . 32 

Spices in vinegar 62 

Stoke, gelatin in milk 3 

Substituted flours 19 

Corn meal in wheat 19 

General test for 19 

Wheat flour in rye 20 

Sulfates in baking powders 24 

Sulfuric acid in vinegar 60 

Sulfurous acid in meat 11 

Stannous chlorid in ginger cake 18 

Starch in fruit and fruit products 4° 

in milk 3 

Tannin in vanilla extracts 5° 

Tartar in vinegar 62 



INDEX 87 

PAGE 

Tartaric acid in baking powders 22, 23 

in cream of tartar 25 

in lemon extract 46 

in wine vinegar 63 

Tea 71 

Adulterations of 71 

Catechu 72 

Exhausted tea leaves 71 

Facing 72 

Foreign leaves 71 

Lie tea 72 

Tocher, sesame oil in olive oil 68 

Turmeric in butter 7 

in lemon extract . < 48 

in mixed pickles 33 

in mustard 55 

Vanderplanken, alum in sour bread 21 

Vanilla extract 48 

Adulterations of 48 

Alkali 49 

Caramel 50 

Coumarin 51 

Foreign resins 49 

Tannin 50 

Vinegar 58 

Adulterations of 58 

Coloring matter 61 

Caramel 61 

Coal-tar colors in wine vinegar 62 

Glucose 63 

Malic acid 61 

Metallic impurities 62 

Mineral acids (free) 59 

Hydrochloric acid 60 

Sulfuric acid 60 

Spices 62 



88 INDEX 

PAGE 

Tartar in wine vinegar 62 

Tartaric acid (free) in wine vinegar 63 

Vogel, substituted flours 19 

Wynther, Blyth, alum in flour 18 

Wolff, tartaric acid free or combined in baking powders 22 



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BYERS, HORACE G., and KNIGHT, HENRY G. Notes 
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R0HLAND, PAUL. The Colloidal and Crystalloidal State 
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ROTH, W. A. Exercises in Physical Chemistry. Author- 
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SEIDELL, A. Solubilities of Inorganic and Organic Sub- 
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SEXTON, A. H. Fuel and Refractory Materials. Second 
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Chemistry of the Materials of Engineering. Illus. 

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SIMMONS, W. H., and MITCHELL, C. A. Edible Fats 
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SINDALL, R. W. The Manufacture of Paper. 58 illus. 
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SINDALL, R. W., and BACON, W. N. The Testing of 
Wood Pulp. A practical handbook for the pulp and 
paper trades. Illus. 8vo. cloth. 150 pp. net, $2.50 

SMITH, J. C. The Manufacture of Paint. A manual for 
paint manufacturers, merchants and painters. Second 
Edition, revised and enlarged. 80 illustrations. 5^ x 
8^4. cloth. 286 pp. t net, $3.50 

SMITH, W. The Chemistry of Hat Manufacturing. 
Revised and edited by Albert Shonk. Illustrated. 
i2mo. cloth. 132 pp. net, $3.00 

S0TJTHC0MBE, J. E. Chemistry of the Oil Industries. 
Illus. 8vo. cloth. 209 pp. net, $3.00 



LIST OF CHEMICAL BOOKS 15 

SPEYERS, C. L. Text-book of Physical Chemistry. 20 

illustrations. 8vo. cloth. 230 pp. net, $2.25 

SPIEGEL, L. Chemical Constitution and Physiological 

Action. Translated by C. Luedeking and A. C. 

Boylston. 5x73/2. cloth. 260 pp. net, $1.25 

STEVENS/ H. P. Paper Mill Chemist. 67 illustrations. 

82 tables. i6mo. cloth. 280 pp. net, $2.50 

SUDB0R0UGH, J. J., and JAMES, J. C. Practical Or- 
ganic Chemistry. 92 illustrations. i2mo. cloth. 

394 pp. net, $2.00 

TERRY, H. L. India Rubber and Its Manufacture. 

18 illustrations. 8vo. cloth. 303 pp. (Van Nos- 

trand's Westminster Series.) net, $2.00 

TITHERLEY, A. W. Laboratory Course of Organic 

Chemistry, Including Qualitative Organic Analysis. 

Illustrated. 8vo. cloth. 235 pp. net, $2.00 

TOCH, M. Chemistry and Technology of Paints. Second 

Edition, revised and enlarged. 111. 6x9. 373 pp. 

net, $4.00 
TOCH, M. Materials for Permanent Painting. A manual 

for manufacturers, art dealers, artists, and collectors. 

With full-page plates. Illustrated. i2mo. cloth. 

208 pp. net, $2.00 

TUCKER, J. H. A Manual of Sugar Analysis. Sixth 

Edition. 43 illustrations. 8vo. cloth. 353 pp. $3.50 
UNDERWOOD, N., and SULLIVAN, T. V. Chemistry and 

Technology of Printing Inks. 9 illustrations. 6x9. 

cloth. 145 pp. net, $3.00 

VAN N0STRANDS Chemical Annual. Edited by John 

C. Olsen and Alfred Melhado. A handbook of useful 

data for analytical manufacturing and investigating 

chemists and chemical students. Third Issue, enlarged. 

5x7^. leather. 683 pp. net, $2.50 

VINCENT, C. Ammonia and Its Compounds. Their 



rt D. VAN NOSTRAND COMPANY'S 

manufacture and uses. Translated from the French 
by M. J. Salter. 32 ill. 8vo. cloth. 113 pp. net, $2.00 

VON GEORGIEVICS, G. Chemical Technology of Textile 
Fibres. Translated from the German by Charles 
Salter. 47 illustrations. 8vo. cloth. 320 pp. net, $4.50 

Chemistry of Dyestuffs. Translated from the Sec- 
ond German Edition by Charles Salter. 8vo. cloth. 
412 pp. net, $4.50 

VOSMAER, A. Ozone, Its Manufacture, Properties and 
Uses. 75 illustrations. 6x9. cloth. 210 pp. net, $2.50 

WADM0RE, J. M. Elementary Chemical Theory. Illus. 
i2mo. cloth. 286 pp. net, $1.50 

WALKER, JAMES. Organic Chemistry for Students of 
Medicine. Illus. 6x9. cloth. 328 pp. net, $2.50 

WALSH, J. J. Mining' and Mine Ventilation. 26 illus. 
8vo. cloth. 192 pp. net, $2.00 

WARNES, A. R. Coal Tar Distillation and Working Up 
of Tar Products. 67 illustrations. 5^x8^4. cloth. 
197 pp. net, $2.50 

WHITE, C. H. Methods in Metallurgical Analysis. 106 

illustrations. 5 x 7^. cloth. 365 pp. net, $2.50 

WHITE, G. F. A Laboratory and Class-room Guide to 
Qualitative Chemical Analysis. 5x7. cloth. 178 pp. 

net, $1.25 

WILSON, F. J., and HEILBR0N, I. M. Chemical Theory 
and Calculations. An elementary text-book. Illus., 3 
folding plates. i2tno. cloth. 145 pp. net, $1.00 

WOOD, J. K. The Chemistry of Dyeing. 5x7^. cloth. 
87 pp. ( Van Nostrand's Chemical Monographs.) 

net, $0.75 

W0RDEN, E. C. The Nitrocellulose Industry. A com- 



LIST OF CHEMICAL BOOKS 



pendium of the history, chemistry, manufacture, com- 
mercial application, and analysis of nitrates, acetates, 
and xanthates of cellulose as applied to the peaceful 
arts. With a chapter on gun cotton, smokeless pow- 
der and explosive cellulose nitrates. Illustrated. 
8vo. cloth. Two, volumes. 1239 pp. net, $10.00 

— Technology of Cellulose Esters. A theoretical and 



practical treatise on the origin, history, chemistry, man- 
ufacture, technical application and analysis of the pro- 
ducts of acylation and alkylation of normal and modi- 
fied cellulose, including nitrocellulose, celluloid, pyr- 
oxylin, collodion, celloidin, gun-cotton, acetycellulose 
and viscose, as applied to technology, pharmacy, 
microscopy, medicine, photography and the warlike 
and peaceful arts. In ten volumes. 600 ill., 12 plates, 
110,000 patent and literature references to the work 
of 12,000 investigators. 

Vol. VIII. Carbohydrate Carboxylates (Cellulose Ace- 
tate). Illustrated. 6^x9^. 515 pp. net, $5.00 
(Other volumes to follow at short intervals.) 
WREN, HENRY. Organometallic Compounds of Zinc and 
Magnesium. 5x7^. cloth. 108 pp. (Van Nos- 
trand's Chemical Monographs.) net, $0.75 



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